diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8fa2ca3b2..95449b591 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ BREAKING CHANGES
 * [stake] remove Tick and add EndBlocker
 
 FEATURES
+* [x/auth] Added AccountNumbers to BaseAccount and StdTxs to allow for replay protection with account pruning
 
 IMPROVEMENTS
 * bank module uses go-wire codec instead of 'encoding/json'
diff --git a/Gopkg.lock b/Gopkg.lock
index 612e8e3b3..07a3c6d5b 100644
--- a/Gopkg.lock
+++ b/Gopkg.lock
@@ -197,8 +197,8 @@
     ".",
     "mem"
   ]
-  revision = "63644898a8da0bc22138abf860edaf5277b6102e"
-  version = "v1.1.0"
+  revision = "787d034dfe70e44075ccc060d346146ef53270ad"
+  version = "v1.1.1"
 
 [[projects]]
   name = "github.com/spf13/cast"
@@ -236,8 +236,8 @@
     "assert",
     "require"
   ]
-  revision = "12b6f73e6084dad08a7c6e575284b177ecafbc71"
-  version = "v1.2.1"
+  revision = "f35b8ab0b5a2cef36673838d662e249dd9c94686"
+  version = "v1.2.2"
 
 [[projects]]
   branch = "master"
@@ -366,7 +366,7 @@
     "merkle",
     "merkle/tmhash"
   ]
-  revision = "640af0205d98d1f45fb2f912f9c35c8bf816adc9"
+  revision = "0c98d10b4ffbd87978d79c160e835b3d3df241ec"
 
 [[projects]]
   branch = "master"
@@ -396,13 +396,13 @@
     "internal/timeseries",
     "trace"
   ]
-  revision = "1e491301e022f8f977054da4c2d852decd59571f"
+  revision = "db08ff08e8622530d9ed3a0e8ac279f6d4c02196"
 
 [[projects]]
   branch = "master"
   name = "golang.org/x/sys"
   packages = ["unix"]
-  revision = "9527bec2660bd847c050fda93a0f0c6dee0800bb"
+  revision = "bff228c7b664c5fce602223a05fb708fd8654986"
 
 [[projects]]
   name = "golang.org/x/text"
diff --git a/client/context/helpers.go b/client/context/helpers.go
index 880c4adb3..0229827fe 100644
--- a/client/context/helpers.go
+++ b/client/context/helpers.go
@@ -109,12 +109,15 @@ func (ctx CoreContext) SignAndBuild(name, passphrase string, msg sdk.Msg, cdc *w
 	if chainID == "" {
 		return nil, errors.Errorf("Chain ID required but not specified")
 	}
+	accnum := ctx.AccountNumber
 	sequence := ctx.Sequence
+
 	signMsg := auth.StdSignMsg{
-		ChainID:   chainID,
-		Sequences: []int64{sequence},
-		Msg:       msg,
-		Fee:       auth.NewStdFee(ctx.Gas, sdk.Coin{}), // TODO run simulate to estimate gas?
+		ChainID:        chainID,
+		AccountNumbers: []int64{accnum},
+		Sequences:      []int64{sequence},
+		Msg:            msg,
+		Fee:            auth.NewStdFee(ctx.Gas, sdk.Coin{}), // TODO run simulate to estimate gas?
 	}
 
 	keybase, err := keys.GetKeyBase()
@@ -130,9 +133,10 @@ func (ctx CoreContext) SignAndBuild(name, passphrase string, msg sdk.Msg, cdc *w
 		return nil, err
 	}
 	sigs := []auth.StdSignature{{
-		PubKey:    pubkey,
-		Signature: sig,
-		Sequence:  sequence,
+		PubKey:        pubkey,
+		Signature:     sig,
+		AccountNumber: accnum,
+		Sequence:      sequence,
 	}}
 
 	// marshal bytes
@@ -144,6 +148,10 @@ func (ctx CoreContext) SignAndBuild(name, passphrase string, msg sdk.Msg, cdc *w
 // sign and build the transaction from the msg
 func (ctx CoreContext) EnsureSignBuildBroadcast(name string, msg sdk.Msg, cdc *wire.Codec) (res *ctypes.ResultBroadcastTxCommit, err error) {
 
+	ctx, err = EnsureAccountNumber(ctx)
+	if err != nil {
+		return nil, err
+	}
 	// default to next sequence number if none provided
 	ctx, err = EnsureSequence(ctx)
 	if err != nil {
@@ -163,13 +171,37 @@ func (ctx CoreContext) EnsureSignBuildBroadcast(name string, msg sdk.Msg, cdc *w
 	return ctx.BroadcastTx(txBytes)
 }
 
+// get the next sequence for the account address
+func (ctx CoreContext) GetAccountNumber(address []byte) (int64, error) {
+	if ctx.Decoder == nil {
+		return 0, errors.New("AccountDecoder required but not provided")
+	}
+
+	res, err := ctx.Query(auth.AddressStoreKey(address), ctx.AccountStore)
+	if err != nil {
+		return 0, err
+	}
+
+	if len(res) == 0 {
+		fmt.Printf("No account found.  Returning 0.\n")
+		return 0, err
+	}
+
+	account, err := ctx.Decoder(res)
+	if err != nil {
+		panic(err)
+	}
+
+	return account.GetAccountNumber(), nil
+}
+
 // get the next sequence for the account address
 func (ctx CoreContext) NextSequence(address []byte) (int64, error) {
 	if ctx.Decoder == nil {
 		return 0, errors.New("AccountDecoder required but not provided")
 	}
 
-	res, err := ctx.Query(address, ctx.AccountStore)
+	res, err := ctx.Query(auth.AddressStoreKey(address), ctx.AccountStore)
 	if err != nil {
 		return 0, err
 	}
diff --git a/client/context/types.go b/client/context/types.go
index e9c97ffbc..791ffb23a 100644
--- a/client/context/types.go
+++ b/client/context/types.go
@@ -14,6 +14,7 @@ type CoreContext struct {
 	TrustNode       bool
 	NodeURI         string
 	FromAddressName string
+	AccountNumber   int64
 	Sequence        int64
 	Client          rpcclient.Client
 	Decoder         auth.AccountDecoder
@@ -57,6 +58,12 @@ func (c CoreContext) WithFromAddressName(fromAddressName string) CoreContext {
 	return c
 }
 
+// WithSequence - return a copy of the context with an account number
+func (c CoreContext) WithAccountNumber(accnum int64) CoreContext {
+	c.AccountNumber = accnum
+	return c
+}
+
 // WithSequence - return a copy of the context with an updated sequence number
 func (c CoreContext) WithSequence(sequence int64) CoreContext {
 	c.Sequence = sequence
diff --git a/client/context/viper.go b/client/context/viper.go
index 081c9f5c2..5f262d56f 100644
--- a/client/context/viper.go
+++ b/client/context/viper.go
@@ -34,6 +34,7 @@ func NewCoreContextFromViper() CoreContext {
 		TrustNode:       viper.GetBool(client.FlagTrustNode),
 		FromAddressName: viper.GetString(client.FlagName),
 		NodeURI:         nodeURI,
+		AccountNumber:   viper.GetInt64(client.FlagAccountNumber),
 		Sequence:        viper.GetInt64(client.FlagSequence),
 		Client:          rpc,
 		Decoder:         nil,
@@ -54,6 +55,25 @@ func defaultChainID() (string, error) {
 	return doc.ChainID, nil
 }
 
+// EnsureSequence - automatically set sequence number if none provided
+func EnsureAccountNumber(ctx CoreContext) (CoreContext, error) {
+	// Should be viper.IsSet, but this does not work - https://github.com/spf13/viper/pull/331
+	if viper.GetInt64(client.FlagAccountNumber) != 0 {
+		return ctx, nil
+	}
+	from, err := ctx.GetFromAddress()
+	if err != nil {
+		return ctx, err
+	}
+	accnum, err := ctx.GetAccountNumber(from)
+	if err != nil {
+		return ctx, err
+	}
+	fmt.Printf("Defaulting to account number: %d\n", accnum)
+	ctx = ctx.WithAccountNumber(accnum)
+	return ctx, nil
+}
+
 // EnsureSequence - automatically set sequence number if none provided
 func EnsureSequence(ctx CoreContext) (CoreContext, error) {
 	// Should be viper.IsSet, but this does not work - https://github.com/spf13/viper/pull/331
diff --git a/client/flags.go b/client/flags.go
index 2d68d3146..4991b9a77 100644
--- a/client/flags.go
+++ b/client/flags.go
@@ -4,14 +4,15 @@ import "github.com/spf13/cobra"
 
 // nolint
 const (
-	FlagChainID   = "chain-id"
-	FlagNode      = "node"
-	FlagHeight    = "height"
-	FlagGas       = "gas"
-	FlagTrustNode = "trust-node"
-	FlagName      = "name"
-	FlagSequence  = "sequence"
-	FlagFee       = "fee"
+	FlagChainID       = "chain-id"
+	FlagNode          = "node"
+	FlagHeight        = "height"
+	FlagGas           = "gas"
+	FlagTrustNode     = "trust-node"
+	FlagName          = "name"
+	FlagAccountNumber = "account-number"
+	FlagSequence      = "sequence"
+	FlagFee           = "fee"
 )
 
 // LineBreak can be included in a command list to provide a blank line
@@ -34,6 +35,7 @@ func GetCommands(cmds ...*cobra.Command) []*cobra.Command {
 func PostCommands(cmds ...*cobra.Command) []*cobra.Command {
 	for _, c := range cmds {
 		c.Flags().String(FlagName, "", "Name of private key with which to sign")
+		c.Flags().Int64(FlagAccountNumber, 0, "AccountNumber number to sign the tx")
 		c.Flags().Int64(FlagSequence, 0, "Sequence number to sign the tx")
 		c.Flags().String(FlagFee, "", "Fee to pay along with transaction")
 		c.Flags().String(FlagChainID, "", "Chain ID of tendermint node")
diff --git a/client/lcd/lcd_test.go b/client/lcd/lcd_test.go
index 48e2ad0a2..946f70bbc 100644
--- a/client/lcd/lcd_test.go
+++ b/client/lcd/lcd_test.go
@@ -423,12 +423,14 @@ func doSend(t *testing.T, port, seed, name, password string, addr sdk.Address) (
 	receiveAddrBech := sdk.MustBech32ifyAcc(receiveAddr)
 
 	acc := getAccount(t, port, addr)
+	accnum := acc.GetAccountNumber()
 	sequence := acc.GetSequence()
 
 	// send
 	jsonStr := []byte(fmt.Sprintf(`{
 		"name":"%s", 
-		"password":"%s", 
+		"password":"%s",
+		"account_number":%d, 
 		"sequence":%d, 
 		"gas": 10000,
 		"amount":[
@@ -437,7 +439,7 @@ func doSend(t *testing.T, port, seed, name, password string, addr sdk.Address) (
 				"amount": 1 
 			}
 		] 
-	}`, name, password, sequence, "steak"))
+	}`, name, password, accnum, sequence, "steak"))
 	res, body := Request(t, port, "POST", "/accounts/"+receiveAddrBech+"/send", jsonStr)
 	require.Equal(t, http.StatusOK, res.StatusCode, body)
 
@@ -457,12 +459,14 @@ func doIBCTransfer(t *testing.T, port, seed, name, password string, addr sdk.Add
 
 	// get the account to get the sequence
 	acc := getAccount(t, port, addr)
+	accnum := acc.GetAccountNumber()
 	sequence := acc.GetSequence()
 
 	// send
 	jsonStr := []byte(fmt.Sprintf(`{ 
 		"name":"%s", 
 		"password": "%s", 
+		"account_number":%d,
 		"sequence": %d, 
 		"gas": 100000,
 		"amount":[
@@ -471,7 +475,7 @@ func doIBCTransfer(t *testing.T, port, seed, name, password string, addr sdk.Add
 				"amount": 1 
 			}
 		] 
-	}`, name, password, sequence, "steak"))
+	}`, name, password, accnum, sequence, "steak"))
 	res, body := Request(t, port, "POST", "/ibc/testchain/"+receiveAddrBech+"/send", jsonStr)
 	require.Equal(t, http.StatusOK, res.StatusCode, body)
 
@@ -498,6 +502,7 @@ func getDelegation(t *testing.T, port string, delegatorAddr, validatorAddr sdk.A
 func doBond(t *testing.T, port, seed, name, password string, delegatorAddr, validatorAddr sdk.Address) (resultTx ctypes.ResultBroadcastTxCommit) {
 	// get the account to get the sequence
 	acc := getAccount(t, port, delegatorAddr)
+	accnum := acc.GetAccountNumber()
 	sequence := acc.GetSequence()
 
 	delegatorAddrBech := sdk.MustBech32ifyAcc(delegatorAddr)
@@ -507,6 +512,7 @@ func doBond(t *testing.T, port, seed, name, password string, delegatorAddr, vali
 	jsonStr := []byte(fmt.Sprintf(`{
 		"name": "%s",
 		"password": "%s",
+		"account_number": %d,
 		"sequence": %d,
 		"gas": 10000,
 		"delegate": [
@@ -517,7 +523,7 @@ func doBond(t *testing.T, port, seed, name, password string, delegatorAddr, vali
 			}
 		],
 		"unbond": []
-	}`, name, password, sequence, delegatorAddrBech, validatorAddrBech, "steak"))
+	}`, name, password, accnum, sequence, delegatorAddrBech, validatorAddrBech, "steak"))
 	res, body := Request(t, port, "POST", "/stake/delegations", jsonStr)
 	require.Equal(t, http.StatusOK, res.StatusCode, body)
 
@@ -531,6 +537,7 @@ func doBond(t *testing.T, port, seed, name, password string, delegatorAddr, vali
 func doUnbond(t *testing.T, port, seed, name, password string, delegatorAddr, validatorAddr sdk.Address) (resultTx ctypes.ResultBroadcastTxCommit) {
 	// get the account to get the sequence
 	acc := getAccount(t, port, delegatorAddr)
+	accnum := acc.GetAccountNumber()
 	sequence := acc.GetSequence()
 
 	delegatorAddrBech := sdk.MustBech32ifyAcc(delegatorAddr)
@@ -540,6 +547,7 @@ func doUnbond(t *testing.T, port, seed, name, password string, delegatorAddr, va
 	jsonStr := []byte(fmt.Sprintf(`{
 		"name": "%s",
 		"password": "%s",
+		"account_number": %d,
 		"sequence": %d,
 		"gas": 10000,
 		"delegate": [],
@@ -550,7 +558,7 @@ func doUnbond(t *testing.T, port, seed, name, password string, delegatorAddr, va
 				"shares": "30"
 			}
 		]
-	}`, name, password, sequence, delegatorAddrBech, validatorAddrBech))
+	}`, name, password, accnum, sequence, delegatorAddrBech, validatorAddrBech))
 	res, body := Request(t, port, "POST", "/stake/delegations", jsonStr)
 	require.Equal(t, http.StatusOK, res.StatusCode, body)
 
diff --git a/cmd/gaia/app/app.go b/cmd/gaia/app/app.go
index f06ed2be3..627eee763 100644
--- a/cmd/gaia/app/app.go
+++ b/cmd/gaia/app/app.go
@@ -82,7 +82,8 @@ func NewGaiaApp(logger log.Logger, db dbm.DB) *GaiaApp {
 	app.Router().
 		AddRoute("bank", bank.NewHandler(app.coinKeeper)).
 		AddRoute("ibc", ibc.NewHandler(app.ibcMapper, app.coinKeeper)).
-		AddRoute("stake", stake.NewHandler(app.stakeKeeper))
+		AddRoute("stake", stake.NewHandler(app.stakeKeeper)).
+		AddRoute("slashing", slashing.NewHandler(app.slashingKeeper))
 
 	// initialize BaseApp
 	app.SetInitChainer(app.initChainer)
@@ -144,6 +145,7 @@ func (app *GaiaApp) initChainer(ctx sdk.Context, req abci.RequestInitChain) abci
 	// load the accounts
 	for _, gacc := range genesisState.Accounts {
 		acc := gacc.ToAccount()
+		acc.AccountNumber = app.accountMapper.GetNextAccountNumber(ctx)
 		app.accountMapper.SetAccount(ctx, acc)
 	}
 
diff --git a/cmd/gaia/app/app_test.go b/cmd/gaia/app/app_test.go
index f79703fef..0523c5499 100644
--- a/cmd/gaia/app/app_test.go
+++ b/cmd/gaia/app/app_test.go
@@ -1,21 +1,11 @@
 package app
 
 import (
-	"os"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/wire"
 	"github.com/cosmos/cosmos-sdk/x/auth"
 	"github.com/cosmos/cosmos-sdk/x/stake"
 
 	abci "github.com/tendermint/abci/types"
-	crypto "github.com/tendermint/go-crypto"
-	dbm "github.com/tendermint/tmlibs/db"
-	"github.com/tendermint/tmlibs/log"
 )
 
 func setGenesis(gapp *GaiaApp, accs ...*auth.BaseAccount) error {
@@ -41,33 +31,3 @@ func setGenesis(gapp *GaiaApp, accs ...*auth.BaseAccount) error {
 
 	return nil
 }
-
-func TestGenesis(t *testing.T) {
-	logger := log.NewTMLogger(log.NewSyncWriter(os.Stdout)).With("module", "sdk/app")
-	db := dbm.NewMemDB()
-	gapp := NewGaiaApp(logger, db)
-
-	// Construct some genesis bytes to reflect GaiaAccount
-	pk := crypto.GenPrivKeyEd25519().PubKey()
-	addr := pk.Address()
-	coins, err := sdk.ParseCoins("77foocoin,99barcoin")
-	require.Nil(t, err)
-	baseAcc := &auth.BaseAccount{
-		Address: addr,
-		Coins:   coins,
-	}
-
-	err = setGenesis(gapp, baseAcc)
-	require.Nil(t, err)
-
-	// A checkTx context
-	ctx := gapp.BaseApp.NewContext(true, abci.Header{})
-	res1 := gapp.accountMapper.GetAccount(ctx, baseAcc.Address)
-	assert.Equal(t, baseAcc, res1)
-
-	// reload app and ensure the account is still there
-	gapp = NewGaiaApp(logger, db)
-	ctx = gapp.BaseApp.NewContext(true, abci.Header{})
-	res1 = gapp.accountMapper.GetAccount(ctx, baseAcc.Address)
-	assert.Equal(t, baseAcc, res1)
-}
diff --git a/docs/sdk/overview.rst b/docs/sdk/overview.rst
index 8a1350906..0cb7e7304 100644
--- a/docs/sdk/overview.rst
+++ b/docs/sdk/overview.rst
@@ -232,12 +232,14 @@ a standard form:
     type StdSignature struct {
     	crypto.PubKey // optional
     	crypto.Signature
-    	Sequence int64
+    	AccountNumber int64
+        Sequence int64
     }
 
-It contains the signature itself, as well as the corresponding account's
-sequence number.  The sequence number is expected to increment every time a
-message is signed by a given account.  This prevents "replay attacks", where
+It contains the signature itself, as well as the corresponding account's account and 
+sequence numbers.  The sequence number is expected to increment every time a
+message is signed by a given account. The account number stays the same and is assigned
+when the account is first generated.  These prevent "replay attacks", where
 the same message could be executed over and over again.
 
 The ``StdSignature`` can also optionally include the public key for verifying the
diff --git a/examples/basecoin/app/app.go b/examples/basecoin/app/app.go
index fdb0638b6..f654ba05e 100644
--- a/examples/basecoin/app/app.go
+++ b/examples/basecoin/app/app.go
@@ -146,6 +146,7 @@ func (app *BasecoinApp) initChainer(ctx sdk.Context, req abci.RequestInitChain)
 			panic(err) // TODO https://github.com/cosmos/cosmos-sdk/issues/468
 			//	return sdk.ErrGenesisParse("").TraceCause(err, "")
 		}
+		acc.AccountNumber = app.accountMapper.GetNextAccountNumber(ctx)
 		app.accountMapper.SetAccount(ctx, acc)
 	}
 
diff --git a/examples/democoin/x/cool/app_test.go b/examples/democoin/x/cool/app_test.go
index d41c8ea82..8d3f347b3 100644
--- a/examples/democoin/x/cool/app_test.go
+++ b/examples/democoin/x/cool/app_test.go
@@ -89,17 +89,17 @@ func TestMsgQuiz(t *testing.T) {
 	assert.Equal(t, acc1, res1)
 
 	// Set the trend, submit a really cool quiz and check for reward
-	mock.SignCheckDeliver(t, mapp.BaseApp, setTrendMsg1, []int64{0}, true, priv1)
-	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg1, []int64{1}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, setTrendMsg1, []int64{0}, []int64{0}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg1, []int64{0}, []int64{1}, true, priv1)
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"icecold", 69}})
-	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg2, []int64{2}, false, priv1) // result without reward
+	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg2, []int64{0}, []int64{2}, false, priv1) // result without reward
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"icecold", 69}})
-	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg1, []int64{3}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg1, []int64{0}, []int64{3}, true, priv1)
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"icecold", 138}})
-	mock.SignCheckDeliver(t, mapp.BaseApp, setTrendMsg2, []int64{4}, true, priv1) // reset the trend
-	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg1, []int64{5}, false, priv1)    // the same answer will nolonger do!
+	mock.SignCheckDeliver(t, mapp.BaseApp, setTrendMsg2, []int64{0}, []int64{4}, true, priv1) // reset the trend
+	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg1, []int64{0}, []int64{5}, false, priv1)    // the same answer will nolonger do!
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"icecold", 138}})
-	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg2, []int64{6}, true, priv1) // earlier answer now relavent again
+	mock.SignCheckDeliver(t, mapp.BaseApp, quizMsg2, []int64{0}, []int64{6}, true, priv1) // earlier answer now relavent again
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"badvibesonly", 69}, {"icecold", 138}})
-	mock.SignCheckDeliver(t, mapp.BaseApp, setTrendMsg3, []int64{7}, false, priv1) // expect to fail to set the trend to something which is not cool
+	mock.SignCheckDeliver(t, mapp.BaseApp, setTrendMsg3, []int64{0}, []int64{7}, false, priv1) // expect to fail to set the trend to something which is not cool
 }
diff --git a/examples/democoin/x/pow/app_test.go b/examples/democoin/x/pow/app_test.go
index 0539df556..aa71fb080 100644
--- a/examples/democoin/x/pow/app_test.go
+++ b/examples/democoin/x/pow/app_test.go
@@ -71,13 +71,13 @@ func TestMsgMine(t *testing.T) {
 
 	// Mine and check for reward
 	mineMsg1 := GenerateMsgMine(addr1, 1, 2)
-	mock.SignCheckDeliver(t, mapp.BaseApp, mineMsg1, []int64{0}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, mineMsg1, []int64{0}, []int64{0}, true, priv1)
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"pow", 1}})
 	// Mine again and check for reward
 	mineMsg2 := GenerateMsgMine(addr1, 2, 3)
-	mock.SignCheckDeliver(t, mapp.BaseApp, mineMsg2, []int64{1}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, mineMsg2, []int64{0}, []int64{1}, true, priv1)
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"pow", 2}})
 	// Mine again - should be invalid
-	mock.SignCheckDeliver(t, mapp.BaseApp, mineMsg2, []int64{1}, false, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, mineMsg2, []int64{0}, []int64{1}, false, priv1)
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"pow", 2}})
 }
diff --git a/x/auth/account.go b/x/auth/account.go
index 0ae72a8a6..77966b8e7 100644
--- a/x/auth/account.go
+++ b/x/auth/account.go
@@ -17,6 +17,9 @@ type Account interface {
 	GetPubKey() crypto.PubKey // can return nil.
 	SetPubKey(crypto.PubKey) error
 
+	GetAccountNumber() int64
+	SetAccountNumber(int64) error
+
 	GetSequence() int64
 	SetSequence(int64) error
 
@@ -36,10 +39,11 @@ var _ Account = (*BaseAccount)(nil)
 // Extend this by embedding this in your AppAccount.
 // See the examples/basecoin/types/account.go for an example.
 type BaseAccount struct {
-	Address  sdk.Address   `json:"address"`
-	Coins    sdk.Coins     `json:"coins"`
-	PubKey   crypto.PubKey `json:"public_key"`
-	Sequence int64         `json:"sequence"`
+	Address       sdk.Address   `json:"address"`
+	Coins         sdk.Coins     `json:"coins"`
+	PubKey        crypto.PubKey `json:"public_key"`
+	AccountNumber int64         `json:"account_number"`
+	Sequence      int64         `json:"sequence"`
 }
 
 func NewBaseAccountWithAddress(addr sdk.Address) BaseAccount {
@@ -84,6 +88,17 @@ func (acc *BaseAccount) SetCoins(coins sdk.Coins) error {
 	return nil
 }
 
+// Implements Account
+func (acc *BaseAccount) GetAccountNumber() int64 {
+	return acc.AccountNumber
+}
+
+// Implements Account
+func (acc *BaseAccount) SetAccountNumber(accNumber int64) error {
+	acc.AccountNumber = accNumber
+	return nil
+}
+
 // Implements sdk.Account.
 func (acc *BaseAccount) GetSequence() int64 {
 	return acc.Sequence
diff --git a/x/auth/ante.go b/x/auth/ante.go
index 9663bcfe4..c50da0c32 100644
--- a/x/auth/ante.go
+++ b/x/auth/ante.go
@@ -14,7 +14,7 @@ const (
 )
 
 // NewAnteHandler returns an AnteHandler that checks
-// and increments sequence numbers, checks signatures,
+// and increments sequence numbers, checks signatures & account numbers,
 // and deducts fees from the first signer.
 func NewAnteHandler(am AccountMapper, fck FeeCollectionKeeper) sdk.AnteHandler {
 
@@ -46,11 +46,15 @@ func NewAnteHandler(am AccountMapper, fck FeeCollectionKeeper) sdk.AnteHandler {
 				true
 		}
 
-		// Get the sign bytes (requires all sequence numbers and the fee)
+		// Get the sign bytes (requires all account & sequence numbers and the fee)
 		sequences := make([]int64, len(signerAddrs))
 		for i := 0; i < len(signerAddrs); i++ {
 			sequences[i] = sigs[i].Sequence
 		}
+		accNums := make([]int64, len(signerAddrs))
+		for i := 0; i < len(signerAddrs); i++ {
+			accNums[i] = sigs[i].AccountNumber
+		}
 		fee := stdTx.Fee
 		chainID := ctx.ChainID()
 		// XXX: major hack; need to get ChainID
@@ -58,7 +62,7 @@ func NewAnteHandler(am AccountMapper, fck FeeCollectionKeeper) sdk.AnteHandler {
 		if chainID == "" {
 			chainID = viper.GetString("chain-id")
 		}
-		signBytes := StdSignBytes(ctx.ChainID(), sequences, fee, msg)
+		signBytes := StdSignBytes(ctx.ChainID(), accNums, sequences, fee, msg)
 
 		// Check sig and nonce and collect signer accounts.
 		var signerAccs = make([]Account, len(signerAddrs))
@@ -117,6 +121,13 @@ func processSig(
 		return nil, sdk.ErrUnknownAddress(addr.String()).Result()
 	}
 
+	// Check account number.
+	accnum := acc.GetAccountNumber()
+	if accnum != sig.AccountNumber {
+		return nil, sdk.ErrInvalidSequence(
+			fmt.Sprintf("Invalid account number. Got %d, expected %d", sig.AccountNumber, accnum)).Result()
+	}
+
 	// Check and increment sequence number.
 	seq := acc.GetSequence()
 	if seq != sig.Sequence {
diff --git a/x/auth/ante_test.go b/x/auth/ante_test.go
index b7f22e5d5..aff80cb59 100644
--- a/x/auth/ante_test.go
+++ b/x/auth/ante_test.go
@@ -52,15 +52,15 @@ func checkInvalidTx(t *testing.T, anteHandler sdk.AnteHandler, ctx sdk.Context,
 	assert.Equal(t, sdk.ToABCICode(sdk.CodespaceRoot, code), result.Code)
 }
 
-func newTestTx(ctx sdk.Context, msg sdk.Msg, privs []crypto.PrivKey, seqs []int64, fee StdFee) sdk.Tx {
-	signBytes := StdSignBytes(ctx.ChainID(), seqs, fee, msg)
-	return newTestTxWithSignBytes(msg, privs, seqs, fee, signBytes)
+func newTestTx(ctx sdk.Context, msg sdk.Msg, privs []crypto.PrivKey, accNums []int64, seqs []int64, fee StdFee) sdk.Tx {
+	signBytes := StdSignBytes(ctx.ChainID(), accNums, seqs, fee, msg)
+	return newTestTxWithSignBytes(msg, privs, accNums, seqs, fee, signBytes)
 }
 
-func newTestTxWithSignBytes(msg sdk.Msg, privs []crypto.PrivKey, seqs []int64, fee StdFee, signBytes []byte) sdk.Tx {
+func newTestTxWithSignBytes(msg sdk.Msg, privs []crypto.PrivKey, accNums []int64, seqs []int64, fee StdFee, signBytes []byte) sdk.Tx {
 	sigs := make([]StdSignature, len(privs))
 	for i, priv := range privs {
-		sigs[i] = StdSignature{PubKey: priv.PubKey(), Signature: priv.Sign(signBytes), Sequence: seqs[i]}
+		sigs[i] = StdSignature{PubKey: priv.PubKey(), Signature: priv.Sign(signBytes), AccountNumber: accNums[i], Sequence: seqs[i]}
 	}
 	tx := NewStdTx(msg, fee, sigs)
 	return tx
@@ -87,18 +87,18 @@ func TestAnteHandlerSigErrors(t *testing.T) {
 	fee := newStdFee()
 
 	// test no signatures
-	privs, seqs := []crypto.PrivKey{}, []int64{}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accNums, seqs := []crypto.PrivKey{}, []int64{}, []int64{}
+	tx = newTestTx(ctx, msg, privs, accNums, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeUnauthorized)
 
 	// test num sigs dont match GetSigners
-	privs, seqs = []crypto.PrivKey{priv1}, []int64{0}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accNums, seqs = []crypto.PrivKey{priv1}, []int64{0}, []int64{0}
+	tx = newTestTx(ctx, msg, privs, accNums, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeUnauthorized)
 
 	// test an unrecognized account
-	privs, seqs = []crypto.PrivKey{priv1, priv2}, []int64{0, 0}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accNums, seqs = []crypto.PrivKey{priv1, priv2}, []int64{0, 1}, []int64{0, 0}
+	tx = newTestTx(ctx, msg, privs, accNums, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeUnknownAddress)
 
 	// save the first account, but second is still unrecognized
@@ -108,6 +108,61 @@ func TestAnteHandlerSigErrors(t *testing.T) {
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeUnknownAddress)
 }
 
+// Test logic around account number checking with one signer and many signers.
+func TestAnteHandlerAccountNumbers(t *testing.T) {
+	// setup
+	ms, capKey, capKey2 := setupMultiStore()
+	cdc := wire.NewCodec()
+	RegisterBaseAccount(cdc)
+	mapper := NewAccountMapper(cdc, capKey, &BaseAccount{})
+	feeCollector := NewFeeCollectionKeeper(cdc, capKey2)
+	anteHandler := NewAnteHandler(mapper, feeCollector)
+	ctx := sdk.NewContext(ms, abci.Header{ChainID: "mychainid"}, false, nil, log.NewNopLogger())
+
+	// keys and addresses
+	priv1, addr1 := privAndAddr()
+	priv2, addr2 := privAndAddr()
+
+	// set the accounts
+	acc1 := mapper.NewAccountWithAddress(ctx, addr1)
+	acc1.SetCoins(newCoins())
+	mapper.SetAccount(ctx, acc1)
+	acc2 := mapper.NewAccountWithAddress(ctx, addr2)
+	acc2.SetCoins(newCoins())
+	mapper.SetAccount(ctx, acc2)
+
+	// msg and signatures
+	var tx sdk.Tx
+	msg := newTestMsg(addr1)
+	fee := newStdFee()
+
+	// test good tx from one signer
+	privs, accnums, seqs := []crypto.PrivKey{priv1}, []int64{0}, []int64{0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
+	checkValidTx(t, anteHandler, ctx, tx)
+
+	// new tx from wrong account number
+	seqs = []int64{1}
+	tx = newTestTx(ctx, msg, privs, []int64{1}, seqs, fee)
+	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeInvalidSequence)
+
+	// from correct account number
+	seqs = []int64{1}
+	tx = newTestTx(ctx, msg, privs, []int64{0}, seqs, fee)
+	checkValidTx(t, anteHandler, ctx, tx)
+
+	// new tx with another signer and incorrect account numbers
+	msg = newTestMsg(addr1, addr2)
+	privs, accnums, seqs = []crypto.PrivKey{priv1, priv2}, []int64{1, 0}, []int64{2, 0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
+	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeInvalidSequence)
+
+	// correct account numbers
+	privs, accnums, seqs = []crypto.PrivKey{priv1, priv2}, []int64{0, 1}, []int64{2, 0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
+	checkValidTx(t, anteHandler, ctx, tx)
+}
+
 // Test logic around sequence checking with one signer and many signers.
 func TestAnteHandlerSequences(t *testing.T) {
 	// setup
@@ -137,8 +192,8 @@ func TestAnteHandlerSequences(t *testing.T) {
 	fee := newStdFee()
 
 	// test good tx from one signer
-	privs, seqs := []crypto.PrivKey{priv1}, []int64{0}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accnums, seqs := []crypto.PrivKey{priv1}, []int64{0}, []int64{0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkValidTx(t, anteHandler, ctx, tx)
 
 	// test sending it again fails (replay protection)
@@ -146,13 +201,13 @@ func TestAnteHandlerSequences(t *testing.T) {
 
 	// fix sequence, should pass
 	seqs = []int64{1}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkValidTx(t, anteHandler, ctx, tx)
 
 	// new tx with another signer and correct sequences
 	msg = newTestMsg(addr1, addr2)
-	privs, seqs = []crypto.PrivKey{priv1, priv2}, []int64{2, 0}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accnums, seqs = []crypto.PrivKey{priv1, priv2}, []int64{0, 1}, []int64{2, 0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkValidTx(t, anteHandler, ctx, tx)
 
 	// replay fails
@@ -160,18 +215,18 @@ func TestAnteHandlerSequences(t *testing.T) {
 
 	// tx from just second signer with incorrect sequence fails
 	msg = newTestMsg(addr2)
-	privs, seqs = []crypto.PrivKey{priv2}, []int64{0}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accnums, seqs = []crypto.PrivKey{priv2}, []int64{1}, []int64{0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeInvalidSequence)
 
 	// fix the sequence and it passes
-	tx = newTestTx(ctx, msg, []crypto.PrivKey{priv2}, []int64{1}, fee)
+	tx = newTestTx(ctx, msg, []crypto.PrivKey{priv2}, []int64{1}, []int64{1}, fee)
 	checkValidTx(t, anteHandler, ctx, tx)
 
 	// another tx from both of them that passes
 	msg = newTestMsg(addr1, addr2)
-	privs, seqs = []crypto.PrivKey{priv1, priv2}, []int64{3, 2}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accnums, seqs = []crypto.PrivKey{priv1, priv2}, []int64{0, 1}, []int64{3, 2}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkValidTx(t, anteHandler, ctx, tx)
 }
 
@@ -196,13 +251,13 @@ func TestAnteHandlerFees(t *testing.T) {
 	// msg and signatures
 	var tx sdk.Tx
 	msg := newTestMsg(addr1)
-	privs, seqs := []crypto.PrivKey{priv1}, []int64{0}
+	privs, accnums, seqs := []crypto.PrivKey{priv1}, []int64{0}, []int64{0}
 	fee := NewStdFee(100,
 		sdk.Coin{"atom", 150},
 	)
 
 	// signer does not have enough funds to pay the fee
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeInsufficientFunds)
 
 	acc1.SetCoins(sdk.Coins{{"atom", 149}})
@@ -249,8 +304,8 @@ func TestAnteHandlerBadSignBytes(t *testing.T) {
 	fee3.Amount[0].Amount += 100
 
 	// test good tx and signBytes
-	privs, seqs := []crypto.PrivKey{priv1}, []int64{0}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accnums, seqs := []crypto.PrivKey{priv1}, []int64{0}, []int64{0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkValidTx(t, anteHandler, ctx, tx)
 
 	chainID := ctx.ChainID()
@@ -259,37 +314,39 @@ func TestAnteHandlerBadSignBytes(t *testing.T) {
 
 	cases := []struct {
 		chainID string
+		accnums []int64
 		seqs    []int64
 		fee     StdFee
 		msg     sdk.Msg
 		code    sdk.CodeType
 	}{
-		{chainID2, []int64{1}, fee, msg, codeUnauth},               // test wrong chain_id
-		{chainID, []int64{2}, fee, msg, codeUnauth},                // test wrong seqs
-		{chainID, []int64{1, 2}, fee, msg, codeUnauth},             // test wrong seqs
-		{chainID, []int64{1}, fee, newTestMsg(addr2), codeUnauth},  // test wrong msg
-		{chainID, []int64{1}, fee2, newTestMsg(addr2), codeUnauth}, // test wrong fee
-		{chainID, []int64{1}, fee3, newTestMsg(addr2), codeUnauth}, // test wrong fee
+		{chainID2, []int64{0}, []int64{1}, fee, msg, codeUnauth},              // test wrong chain_id
+		{chainID, []int64{0}, []int64{2}, fee, msg, codeUnauth},               // test wrong seqs
+		{chainID, []int64{0}, []int64{1, 2}, fee, msg, codeUnauth},            // test wrong seqs
+		{chainID, []int64{1}, []int64{1}, fee, msg, codeUnauth},               // test wrong accnum
+		{chainID, []int64{0}, []int64{1}, fee, newTestMsg(addr2), codeUnauth}, // test wrong msg
+		{chainID, []int64{0}, []int64{1}, fee2, msg, codeUnauth},              // test wrong fee
+		{chainID, []int64{0}, []int64{1}, fee3, msg, codeUnauth},              // test wrong fee
 	}
 
 	privs, seqs = []crypto.PrivKey{priv1}, []int64{1}
 	for _, cs := range cases {
 		tx := newTestTxWithSignBytes(
-			msg, privs, seqs, fee,
-			StdSignBytes(cs.chainID, cs.seqs, cs.fee, cs.msg),
+			msg, privs, accnums, seqs, fee,
+			StdSignBytes(cs.chainID, cs.accnums, cs.seqs, cs.fee, cs.msg),
 		)
 		checkInvalidTx(t, anteHandler, ctx, tx, cs.code)
 	}
 
 	// test wrong signer if public key exist
-	privs, seqs = []crypto.PrivKey{priv2}, []int64{1}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accnums, seqs = []crypto.PrivKey{priv2}, []int64{0}, []int64{1}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeUnauthorized)
 
 	// test wrong signer if public doesn't exist
 	msg = newTestMsg(addr2)
-	privs, seqs = []crypto.PrivKey{priv1}, []int64{0}
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	privs, accnums, seqs = []crypto.PrivKey{priv1}, []int64{1}, []int64{0}
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeInvalidPubKey)
 
 }
@@ -320,9 +377,9 @@ func TestAnteHandlerSetPubKey(t *testing.T) {
 
 	// test good tx and set public key
 	msg := newTestMsg(addr1)
-	privs, seqs := []crypto.PrivKey{priv1}, []int64{0}
+	privs, accnums, seqs := []crypto.PrivKey{priv1}, []int64{0}, []int64{0}
 	fee := newStdFee()
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	tx = newTestTx(ctx, msg, privs, accnums, seqs, fee)
 	checkValidTx(t, anteHandler, ctx, tx)
 
 	acc1 = mapper.GetAccount(ctx, addr1)
@@ -330,7 +387,7 @@ func TestAnteHandlerSetPubKey(t *testing.T) {
 
 	// test public key not found
 	msg = newTestMsg(addr2)
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	tx = newTestTx(ctx, msg, privs, []int64{1}, seqs, fee)
 	sigs := tx.(StdTx).GetSignatures()
 	sigs[0].PubKey = nil
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeInvalidPubKey)
@@ -339,7 +396,7 @@ func TestAnteHandlerSetPubKey(t *testing.T) {
 	assert.Nil(t, acc2.GetPubKey())
 
 	// test invalid signature and public key
-	tx = newTestTx(ctx, msg, privs, seqs, fee)
+	tx = newTestTx(ctx, msg, privs, []int64{1}, seqs, fee)
 	checkInvalidTx(t, anteHandler, ctx, tx, sdk.CodeInvalidPubKey)
 
 	acc2 = mapper.GetAccount(ctx, addr2)
diff --git a/x/auth/client/cli/account.go b/x/auth/client/cli/account.go
index e82b07414..a3265a78c 100644
--- a/x/auth/client/cli/account.go
+++ b/x/auth/client/cli/account.go
@@ -47,7 +47,7 @@ func GetAccountCmd(storeName string, cdc *wire.Codec, decoder auth.AccountDecode
 
 			// perform query
 			ctx := context.NewCoreContextFromViper()
-			res, err := ctx.Query(key, storeName)
+			res, err := ctx.Query(auth.AddressStoreKey(key), storeName)
 			if err != nil {
 				return err
 			}
diff --git a/x/auth/client/rest/query.go b/x/auth/client/rest/query.go
index bcae59c20..9ccbe8e14 100644
--- a/x/auth/client/rest/query.go
+++ b/x/auth/client/rest/query.go
@@ -34,7 +34,7 @@ func QueryAccountRequestHandlerFn(storeName string, cdc *wire.Codec, decoder aut
 			return
 		}
 
-		res, err := ctx.Query(addr, storeName)
+		res, err := ctx.Query(auth.AddressStoreKey(addr), storeName)
 		if err != nil {
 			w.WriteHeader(http.StatusInternalServerError)
 			w.Write([]byte(fmt.Sprintf("Could't query account. Error: %s", err.Error())))
diff --git a/x/auth/mapper.go b/x/auth/mapper.go
index cdab2480e..b4364f768 100644
--- a/x/auth/mapper.go
+++ b/x/auth/mapper.go
@@ -9,6 +9,8 @@ import (
 	crypto "github.com/tendermint/go-crypto"
 )
 
+var globalAccountNumberKey = []byte("globalAccountNumber")
+
 // This AccountMapper encodes/decodes accounts using the
 // go-amino (binary) encoding/decoding library.
 type AccountMapper struct {
@@ -38,13 +40,25 @@ func NewAccountMapper(cdc *wire.Codec, key sdk.StoreKey, proto Account) AccountM
 func (am AccountMapper) NewAccountWithAddress(ctx sdk.Context, addr sdk.Address) Account {
 	acc := am.clonePrototype()
 	acc.SetAddress(addr)
+	acc.SetAccountNumber(am.GetNextAccountNumber(ctx))
 	return acc
 }
 
+// New Account
+func (am AccountMapper) NewAccount(ctx sdk.Context, acc Account) Account {
+	acc.SetAccountNumber(am.GetNextAccountNumber(ctx))
+	return acc
+}
+
+// Turn an address to key used to get it from the account store
+func AddressStoreKey(addr sdk.Address) []byte {
+	return append([]byte("account:"), addr.Bytes()...)
+}
+
 // Implements sdk.AccountMapper.
 func (am AccountMapper) GetAccount(ctx sdk.Context, addr sdk.Address) Account {
 	store := ctx.KVStore(am.key)
-	bz := store.Get(addr)
+	bz := store.Get(AddressStoreKey(addr))
 	if bz == nil {
 		return nil
 	}
@@ -57,13 +71,13 @@ func (am AccountMapper) SetAccount(ctx sdk.Context, acc Account) {
 	addr := acc.GetAddress()
 	store := ctx.KVStore(am.key)
 	bz := am.encodeAccount(acc)
-	store.Set(addr, bz)
+	store.Set(AddressStoreKey(addr), bz)
 }
 
 // Implements sdk.AccountMapper.
 func (am AccountMapper) IterateAccounts(ctx sdk.Context, process func(Account) (stop bool)) {
 	store := ctx.KVStore(am.key)
-	iter := store.Iterator(nil, nil)
+	iter := sdk.KVStorePrefixIterator(store, []byte("account:"))
 	for {
 		if !iter.Valid() {
 			return
@@ -116,6 +130,26 @@ func (am AccountMapper) setSequence(ctx sdk.Context, addr sdk.Address, newSequen
 	return nil
 }
 
+// Returns and increments the global account number counter
+func (am AccountMapper) GetNextAccountNumber(ctx sdk.Context) int64 {
+	var accNumber int64
+	store := ctx.KVStore(am.key)
+	bz := store.Get(globalAccountNumberKey)
+	if bz == nil {
+		accNumber = 0
+	} else {
+		err := am.cdc.UnmarshalBinary(bz, &accNumber)
+		if err != nil {
+			panic(err)
+		}
+	}
+
+	bz = am.cdc.MustMarshalBinary(accNumber + 1)
+	store.Set(globalAccountNumberKey, bz)
+
+	return accNumber
+}
+
 //----------------------------------------
 // misc.
 
diff --git a/x/auth/mock/app.go b/x/auth/mock/app.go
index fcd130b44..953008807 100644
--- a/x/auth/mock/app.go
+++ b/x/auth/mock/app.go
@@ -78,7 +78,9 @@ func (app *App) CompleteSetup(t *testing.T, newKeys []*sdk.KVStoreKey) {
 func (app *App) InitChainer(ctx sdk.Context, _ abci.RequestInitChain) abci.ResponseInitChain {
 
 	// load the accounts
-	for _, acc := range app.GenesisAccounts {
+	for _, genacc := range app.GenesisAccounts {
+		acc := app.AccountMapper.NewAccountWithAddress(ctx, genacc.GetAddress())
+		acc.SetCoins(genacc.GetCoins())
 		app.AccountMapper.SetAccount(ctx, acc)
 	}
 
diff --git a/x/auth/mock/auth_app_test.go b/x/auth/mock/auth_app_test.go
index 716037d60..bb4d7007b 100644
--- a/x/auth/mock/auth_app_test.go
+++ b/x/auth/mock/auth_app_test.go
@@ -61,7 +61,7 @@ func TestMsgChangePubKey(t *testing.T) {
 	assert.Equal(t, acc1, res1.(*auth.BaseAccount))
 
 	// Run a CheckDeliver
-	SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, true, priv1)
+	SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, []int64{0}, true, priv1)
 
 	// Check balances
 	CheckBalance(t, mapp, addr1, sdk.Coins{{"foocoin", 67}})
@@ -77,19 +77,19 @@ func TestMsgChangePubKey(t *testing.T) {
 	acc2 := mapp.AccountMapper.GetAccount(ctxDeliver, addr1)
 
 	// send a MsgChangePubKey
-	SignCheckDeliver(t, mapp.BaseApp, changePubKeyMsg, []int64{1}, true, priv1)
+	SignCheckDeliver(t, mapp.BaseApp, changePubKeyMsg, []int64{0}, []int64{1}, true, priv1)
 	acc2 = mapp.AccountMapper.GetAccount(ctxDeliver, addr1)
 
 	assert.True(t, priv2.PubKey().Equals(acc2.GetPubKey()))
 
 	// signing a SendMsg with the old privKey should be an auth error
 	mapp.BeginBlock(abci.RequestBeginBlock{})
-	tx := GenTx(sendMsg1, []int64{2}, priv1)
+	tx := GenTx(sendMsg1, []int64{0}, []int64{2}, priv1)
 	res := mapp.Deliver(tx)
 	assert.Equal(t, sdk.ToABCICode(sdk.CodespaceRoot, sdk.CodeUnauthorized), res.Code, res.Log)
 
 	// resigning the tx with the new correct priv key should work
-	SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{2}, true, priv2)
+	SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, []int64{2}, true, priv2)
 
 	// Check balances
 	CheckBalance(t, mapp, addr1, sdk.Coins{{"foocoin", 57}})
diff --git a/x/auth/mock/simulate_block.go b/x/auth/mock/simulate_block.go
index 72ec8411f..7a77e0f09 100644
--- a/x/auth/mock/simulate_block.go
+++ b/x/auth/mock/simulate_block.go
@@ -33,7 +33,7 @@ func CheckBalance(t *testing.T, app *App, addr sdk.Address, exp sdk.Coins) {
 }
 
 // generate a signed transaction
-func GenTx(msg sdk.Msg, seq []int64, priv ...crypto.PrivKeyEd25519) auth.StdTx {
+func GenTx(msg sdk.Msg, accnums []int64, seq []int64, priv ...crypto.PrivKeyEd25519) auth.StdTx {
 
 	// make the transaction free
 	fee := auth.StdFee{
@@ -44,19 +44,27 @@ func GenTx(msg sdk.Msg, seq []int64, priv ...crypto.PrivKeyEd25519) auth.StdTx {
 	sigs := make([]auth.StdSignature, len(priv))
 	for i, p := range priv {
 		sigs[i] = auth.StdSignature{
-			PubKey:    p.PubKey(),
-			Signature: p.Sign(auth.StdSignBytes(chainID, seq, fee, msg)),
-			Sequence:  seq[i],
+			PubKey:        p.PubKey(),
+			Signature:     p.Sign(auth.StdSignBytes(chainID, accnums, seq, fee, msg)),
+			AccountNumber: accnums[i],
+			Sequence:      seq[i],
 		}
 	}
 	return auth.NewStdTx(msg, fee, sigs)
 }
 
+// check a transaction result
+func SignCheck(t *testing.T, app *baseapp.BaseApp, msg sdk.Msg, accnums []int64, seq []int64, priv ...crypto.PrivKeyEd25519) sdk.Result {
+	tx := GenTx(msg, accnums, seq, priv...)
+	res := app.Check(tx)
+	return res
+}
+
 // simulate a block
-func SignCheckDeliver(t *testing.T, app *baseapp.BaseApp, msg sdk.Msg, seq []int64, expPass bool, priv ...crypto.PrivKeyEd25519) {
+func SignCheckDeliver(t *testing.T, app *baseapp.BaseApp, msg sdk.Msg, accnums []int64, seq []int64, expPass bool, priv ...crypto.PrivKeyEd25519) {
 
 	// Sign the tx
-	tx := GenTx(msg, seq, priv...)
+	tx := GenTx(msg, accnums, seq, priv...)
 
 	// Run a Check
 	res := app.Check(tx)
diff --git a/x/auth/stdtx.go b/x/auth/stdtx.go
index e08f77ee4..5c43a3717 100644
--- a/x/auth/stdtx.go
+++ b/x/auth/stdtx.go
@@ -85,21 +85,23 @@ func (fee StdFee) Bytes() []byte {
 // and the Sequence numbers for each signature (prevent
 // inchain replay and enforce tx ordering per account).
 type StdSignDoc struct {
-	ChainID   string          `json:"chain_id"`
-	Sequences []int64         `json:"sequences"`
-	FeeBytes  json.RawMessage `json:"fee_bytes"`
-	MsgBytes  json.RawMessage `json:"msg_bytes"`
-	AltBytes  json.RawMessage `json:"alt_bytes"`
+	ChainID        string  `json:"chain_id"`
+	AccountNumbers []int64 `json:"account_numbers"`
+	Sequences      []int64 `json:"sequences"`
+	FeeBytes       []byte  `json:"fee_bytes"`
+	MsgBytes       []byte  `json:"msg_bytes"`
+	AltBytes       []byte  `json:"alt_bytes"`
 }
 
 // StdSignBytes returns the bytes to sign for a transaction.
 // TODO: change the API to just take a chainID and StdTx ?
-func StdSignBytes(chainID string, sequences []int64, fee StdFee, msg sdk.Msg) []byte {
-	bz, err := msgCdc.MarshalJSON(StdSignDoc{
-		ChainID:   chainID,
-		Sequences: sequences,
-		FeeBytes:  json.RawMessage(fee.Bytes()),
-		MsgBytes:  json.RawMessage(msg.GetSignBytes()),
+func StdSignBytes(chainID string, accnums []int64, sequences []int64, fee StdFee, msg sdk.Msg) []byte {
+	bz, err := json.Marshal(StdSignDoc{
+		ChainID:        chainID,
+		AccountNumbers: accnums,
+		Sequences:      sequences,
+		FeeBytes:       fee.Bytes(),
+		MsgBytes:       msg.GetSignBytes(),
 	})
 	if err != nil {
 		panic(err)
@@ -111,21 +113,23 @@ func StdSignBytes(chainID string, sequences []int64, fee StdFee, msg sdk.Msg) []
 // a Msg with the other requirements for a StdSignDoc before
 // it is signed. For use in the CLI.
 type StdSignMsg struct {
-	ChainID   string
-	Sequences []int64
-	Fee       StdFee
-	Msg       sdk.Msg
+	ChainID        string
+	AccountNumbers []int64
+	Sequences      []int64
+	Fee            StdFee
+	Msg            sdk.Msg
 	// XXX: Alt
 }
 
 // get message bytes
 func (msg StdSignMsg) Bytes() []byte {
-	return StdSignBytes(msg.ChainID, msg.Sequences, msg.Fee, msg.Msg)
+	return StdSignBytes(msg.ChainID, msg.AccountNumbers, msg.Sequences, msg.Fee, msg.Msg)
 }
 
 // Standard Signature
 type StdSignature struct {
 	crypto.PubKey    `json:"pub_key"` // optional
 	crypto.Signature `json:"signature"`
+	AccountNumber    int64 `json:"account_number"`
 	Sequence         int64 `json:"sequence"`
 }
diff --git a/x/bank/app_test.go b/x/bank/app_test.go
index 21d7d03a0..d0c112b3d 100644
--- a/x/bank/app_test.go
+++ b/x/bank/app_test.go
@@ -107,25 +107,25 @@ func TestMsgSendWithAccounts(t *testing.T) {
 	assert.Equal(t, acc, res1.(*auth.BaseAccount))
 
 	// Run a CheckDeliver
-	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, []int64{0}, true, priv1)
 
 	// Check balances
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"foocoin", 57}})
 	mock.CheckBalance(t, mapp, addr2, sdk.Coins{{"foocoin", 10}})
 
 	// Delivering again should cause replay error
-	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, false, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, []int64{0}, false, priv1)
 
 	// bumping the txnonce number without resigning should be an auth error
 	mapp.BeginBlock(abci.RequestBeginBlock{})
-	tx := mock.GenTx(sendMsg1, []int64{0}, priv1)
+	tx := mock.GenTx(sendMsg1, []int64{0}, []int64{0}, priv1)
 	tx.Signatures[0].Sequence = 1
 	res := mapp.Deliver(tx)
 
 	assert.Equal(t, sdk.ToABCICode(sdk.CodespaceRoot, sdk.CodeUnauthorized), res.Code, res.Log)
 
 	// resigning the tx with the bumped sequence should work
-	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{1}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, []int64{1}, true, priv1)
 }
 
 func TestMsgSendMultipleOut(t *testing.T) {
@@ -145,7 +145,7 @@ func TestMsgSendMultipleOut(t *testing.T) {
 	mock.SetGenesis(mapp, accs)
 
 	// Simulate a Block
-	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg2, []int64{0}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg2, []int64{0}, []int64{0}, true, priv1)
 
 	// Check balances
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"foocoin", 32}})
@@ -173,7 +173,7 @@ func TestSengMsgMultipleInOut(t *testing.T) {
 	mock.SetGenesis(mapp, accs)
 
 	// CheckDeliver
-	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg3, []int64{0, 0}, true, priv1, priv4)
+	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg3, []int64{0, 2}, []int64{0, 0}, true, priv1, priv4)
 
 	// Check balances
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"foocoin", 32}})
@@ -194,14 +194,14 @@ func TestMsgSendDependent(t *testing.T) {
 	mock.SetGenesis(mapp, accs)
 
 	// CheckDeliver
-	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg1, []int64{0}, []int64{0}, true, priv1)
 
 	// Check balances
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"foocoin", 32}})
 	mock.CheckBalance(t, mapp, addr2, sdk.Coins{{"foocoin", 10}})
 
 	// Simulate a Block
-	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg4, []int64{0}, true, priv2)
+	mock.SignCheckDeliver(t, mapp.BaseApp, sendMsg4, []int64{1}, []int64{0}, true, priv2)
 
 	// Check balances
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{{"foocoin", 42}})
diff --git a/x/bank/client/rest/sendtx.go b/x/bank/client/rest/sendtx.go
index 28a294617..2639d2788 100644
--- a/x/bank/client/rest/sendtx.go
+++ b/x/bank/client/rest/sendtx.go
@@ -27,6 +27,7 @@ type sendBody struct {
 	LocalAccountName string    `json:"name"`
 	Password         string    `json:"password"`
 	ChainID          string    `json:"chain_id"`
+	AccountNumber    int64     `json:"account_number"`
 	Sequence         int64     `json:"sequence"`
 	Gas              int64     `json:"gas"`
 }
@@ -91,6 +92,7 @@ func SendRequestHandlerFn(cdc *wire.Codec, kb keys.Keybase, ctx context.CoreCont
 		ctx = ctx.WithGas(m.Gas)
 
 		// sign
+		ctx = ctx.WithAccountNumber(m.AccountNumber)
 		ctx = ctx.WithSequence(m.Sequence)
 		txBytes, err := ctx.SignAndBuild(m.LocalAccountName, m.Password, msg, cdc)
 		if err != nil {
diff --git a/x/ibc/app_test.go b/x/ibc/app_test.go
index 9e4b4bf56..90d426882 100644
--- a/x/ibc/app_test.go
+++ b/x/ibc/app_test.go
@@ -5,9 +5,9 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
-	"github.com/cosmos/cosmos-sdk/x/auth/mock"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
+	"github.com/cosmos/cosmos-sdk/x/auth/mock"
 	"github.com/cosmos/cosmos-sdk/x/bank"
 
 	abci "github.com/tendermint/abci/types"
@@ -70,10 +70,10 @@ func TestIBCMsgs(t *testing.T) {
 		Sequence:  0,
 	}
 
-	mock.SignCheckDeliver(t, mapp.BaseApp, transferMsg, []int64{0}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, transferMsg, []int64{0},[]int64{0}, true, priv1)
 	mock.CheckBalance(t, mapp, addr1, emptyCoins)
-	mock.SignCheckDeliver(t, mapp.BaseApp, transferMsg, []int64{1}, false, priv1)
-	mock.SignCheckDeliver(t, mapp.BaseApp, receiveMsg, []int64{2}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, transferMsg, []int64{0}, []int64{1}, false, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, receiveMsg, []int64{0}, []int64{2}, true, priv1)
 	mock.CheckBalance(t, mapp, addr1, coins)
-	mock.SignCheckDeliver(t, mapp.BaseApp, receiveMsg, []int64{3}, false, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, receiveMsg, []int64{0}, []int64{3}, false, priv1)
 }
diff --git a/x/ibc/client/rest/transfer.go b/x/ibc/client/rest/transfer.go
index 2b26b9f01..b77a6f5eb 100644
--- a/x/ibc/client/rest/transfer.go
+++ b/x/ibc/client/rest/transfer.go
@@ -25,6 +25,7 @@ type transferBody struct {
 	LocalAccountName string    `json:"name"`
 	Password         string    `json:"password"`
 	SrcChainID       string    `json:"src_chain_id"`
+	AccountNumber    int64     `json:"account_number"`
 	Sequence         int64     `json:"sequence"`
 	Gas              int64     `json:"gas"`
 }
@@ -82,6 +83,7 @@ func TransferRequestHandlerFn(cdc *wire.Codec, kb keys.Keybase, ctx context.Core
 		ctx = ctx.WithGas(m.Gas)
 
 		// sign
+		ctx = ctx.WithAccountNumber(m.AccountNumber)
 		ctx = ctx.WithSequence(m.Sequence)
 		txBytes, err := ctx.SignAndBuild(m.LocalAccountName, m.Password, msg, cdc)
 		if err != nil {
diff --git a/x/slashing/app_test.go b/x/slashing/app_test.go
new file mode 100644
index 000000000..2a99795c6
--- /dev/null
+++ b/x/slashing/app_test.go
@@ -0,0 +1,111 @@
+package slashing
+
+import (
+	"testing"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/auth"
+	"github.com/cosmos/cosmos-sdk/x/auth/mock"
+	"github.com/cosmos/cosmos-sdk/x/bank"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/cosmos/cosmos-sdk/x/stake"
+	abci "github.com/tendermint/abci/types"
+	crypto "github.com/tendermint/go-crypto"
+)
+
+var (
+	priv1 = crypto.GenPrivKeyEd25519()
+	addr1 = priv1.PubKey().Address()
+	coins = sdk.Coins{{"foocoin", 10}}
+)
+
+// initialize the mock application for this module
+func getMockApp(t *testing.T) (*mock.App, stake.Keeper, Keeper) {
+	mapp := mock.NewApp()
+
+	RegisterWire(mapp.Cdc)
+	keyStake := sdk.NewKVStoreKey("stake")
+	keySlashing := sdk.NewKVStoreKey("slashing")
+	coinKeeper := bank.NewKeeper(mapp.AccountMapper)
+	stakeKeeper := stake.NewKeeper(mapp.Cdc, keyStake, coinKeeper, mapp.RegisterCodespace(stake.DefaultCodespace))
+	keeper := NewKeeper(mapp.Cdc, keySlashing, stakeKeeper, mapp.RegisterCodespace(DefaultCodespace))
+	mapp.Router().AddRoute("stake", stake.NewHandler(stakeKeeper))
+	mapp.Router().AddRoute("slashing", NewHandler(keeper))
+
+	mapp.SetEndBlocker(getEndBlocker(stakeKeeper))
+	mapp.SetInitChainer(getInitChainer(mapp, stakeKeeper))
+	mapp.CompleteSetup(t, []*sdk.KVStoreKey{keyStake, keySlashing})
+
+	return mapp, stakeKeeper, keeper
+}
+
+// stake endblocker
+func getEndBlocker(keeper stake.Keeper) sdk.EndBlocker {
+	return func(ctx sdk.Context, req abci.RequestEndBlock) abci.ResponseEndBlock {
+		validatorUpdates := stake.EndBlocker(ctx, keeper)
+		return abci.ResponseEndBlock{
+			ValidatorUpdates: validatorUpdates,
+		}
+	}
+}
+
+// overwrite the mock init chainer
+func getInitChainer(mapp *mock.App, keeper stake.Keeper) sdk.InitChainer {
+	return func(ctx sdk.Context, req abci.RequestInitChain) abci.ResponseInitChain {
+		mapp.InitChainer(ctx, req)
+		stake.InitGenesis(ctx, keeper, stake.DefaultGenesisState())
+		return abci.ResponseInitChain{}
+	}
+}
+
+func checkValidator(t *testing.T, mapp *mock.App, keeper stake.Keeper,
+	addr sdk.Address, expFound bool) stake.Validator {
+	ctxCheck := mapp.BaseApp.NewContext(true, abci.Header{})
+	validator, found := keeper.GetValidator(ctxCheck, addr1)
+	assert.Equal(t, expFound, found)
+	return validator
+}
+
+func checkValidatorSigningInfo(t *testing.T, mapp *mock.App, keeper Keeper,
+	addr sdk.Address, expFound bool) ValidatorSigningInfo {
+	ctxCheck := mapp.BaseApp.NewContext(true, abci.Header{})
+	signingInfo, found := keeper.getValidatorSigningInfo(ctxCheck, addr)
+	assert.Equal(t, expFound, found)
+	return signingInfo
+}
+
+func TestSlashingMsgs(t *testing.T) {
+	mapp, stakeKeeper, keeper := getMockApp(t)
+
+	genCoin := sdk.Coin{"steak", 42}
+	bondCoin := sdk.Coin{"steak", 10}
+
+	acc1 := &auth.BaseAccount{
+		Address: addr1,
+		Coins:   sdk.Coins{genCoin},
+	}
+	accs := []auth.Account{acc1}
+	mock.SetGenesis(mapp, accs)
+	description := stake.NewDescription("foo_moniker", "", "", "")
+	createValidatorMsg := stake.NewMsgCreateValidator(
+		addr1, priv1.PubKey(), bondCoin, description,
+	)
+	mock.SignCheckDeliver(t, mapp.BaseApp, createValidatorMsg, []int64{0}, []int64{0}, true, priv1)
+	mock.CheckBalance(t, mapp, addr1, sdk.Coins{genCoin.Minus(bondCoin)})
+	mapp.BeginBlock(abci.RequestBeginBlock{})
+
+	validator := checkValidator(t, mapp, stakeKeeper, addr1, true)
+	require.Equal(t, addr1, validator.Owner)
+	require.Equal(t, sdk.Bonded, validator.Status())
+	require.True(sdk.RatEq(t, sdk.NewRat(10), validator.PoolShares.Bonded()))
+	unrevokeMsg := MsgUnrevoke{ValidatorAddr: validator.PubKey.Address()}
+
+	// no signing info yet
+	checkValidatorSigningInfo(t, mapp, keeper, addr1, false)
+
+	// unrevoke should fail with unknown validator
+	res := mock.SignCheck(t, mapp.BaseApp, unrevokeMsg, []int64{0}, []int64{1}, priv1)
+	require.Equal(t, sdk.ToABCICode(DefaultCodespace, CodeInvalidValidator), res.Code)
+}
diff --git a/x/slashing/keeper.go b/x/slashing/keeper.go
index d558cc04b..d5ae09ef2 100644
--- a/x/slashing/keeper.go
+++ b/x/slashing/keeper.go
@@ -55,8 +55,12 @@ func (k Keeper) handleValidatorSignature(ctx sdk.Context, pubkey crypto.PubKey,
 	address := pubkey.Address()
 
 	// Local index, so counts blocks validator *should* have signed
-	// Will use the 0-value default signing info if not present
-	signInfo, _ := k.getValidatorSigningInfo(ctx, address)
+	// Will use the 0-value default signing info if not present, except for start height
+	signInfo, found := k.getValidatorSigningInfo(ctx, address)
+	if !found {
+		// If this validator has never been seen before, construct a new SigningInfo with the correct start height
+		signInfo = NewValidatorSigningInfo(height, 0, 0, 0)
+	}
 	index := signInfo.IndexOffset % SignedBlocksWindow
 	signInfo.IndexOffset++
 
diff --git a/x/slashing/keeper_test.go b/x/slashing/keeper_test.go
index 25ae1686d..1f8f9db07 100644
--- a/x/slashing/keeper_test.go
+++ b/x/slashing/keeper_test.go
@@ -11,6 +11,8 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/stake"
 )
 
+// Test that a validator is slashed correctly
+// when we discover evidence of equivocation
 func TestHandleDoubleSign(t *testing.T) {
 
 	// initial setup
@@ -32,6 +34,8 @@ func TestHandleDoubleSign(t *testing.T) {
 	require.Equal(t, sdk.NewRat(amt).Mul(sdk.NewRat(19).Quo(sdk.NewRat(20))), sk.Validator(ctx, addr).GetPower())
 }
 
+// Test a validator through uptime, downtime, revocation,
+// unrevocation, starting height reset, and revocation again
 func TestHandleAbsentValidator(t *testing.T) {
 
 	// initial setup
@@ -129,3 +133,39 @@ func TestHandleAbsentValidator(t *testing.T) {
 	validator, _ = sk.GetValidatorByPubKey(ctx, val)
 	require.Equal(t, sdk.Unbonded, validator.GetStatus())
 }
+
+// Test a new validator entering the validator set
+// Ensure that SigningInfo.StartHeight is set correctly
+// and that they are not immediately revoked
+func TestHandleNewValidator(t *testing.T) {
+	// initial setup
+	ctx, ck, sk, keeper := createTestInput(t)
+	addr, val, amt := addrs[0], pks[0], int64(100)
+	sh := stake.NewHandler(sk)
+	got := sh(ctx, newTestMsgCreateValidator(addr, val, amt))
+	require.True(t, got.IsOK())
+	stake.EndBlocker(ctx, sk)
+	require.Equal(t, ck.GetCoins(ctx, addr), sdk.Coins{{sk.GetParams(ctx).BondDenom, initCoins - amt}})
+	require.Equal(t, sdk.NewRat(amt), sk.Validator(ctx, addr).GetPower())
+
+	// 1000 first blocks not a validator
+	ctx = ctx.WithBlockHeight(1001)
+
+	// Now a validator, for two blocks
+	keeper.handleValidatorSignature(ctx, val, true)
+	ctx = ctx.WithBlockHeight(1002)
+	keeper.handleValidatorSignature(ctx, val, false)
+
+	info, found := keeper.getValidatorSigningInfo(ctx, val.Address())
+	require.True(t, found)
+	require.Equal(t, int64(1001), info.StartHeight)
+	require.Equal(t, int64(2), info.IndexOffset)
+	require.Equal(t, int64(1), info.SignedBlocksCounter)
+	require.Equal(t, int64(0), info.JailedUntil)
+
+	// validator should be bonded still, should not have been revoked or slashed
+	validator, _ := sk.GetValidatorByPubKey(ctx, val)
+	require.Equal(t, sdk.Bonded, validator.GetStatus())
+	pool := sk.GetPool(ctx)
+	require.Equal(t, int64(100), pool.BondedTokens)
+}
diff --git a/x/slashing/signing_info.go b/x/slashing/signing_info.go
index a2df0505a..acbe1738b 100644
--- a/x/slashing/signing_info.go
+++ b/x/slashing/signing_info.go
@@ -47,6 +47,16 @@ func (k Keeper) setValidatorSigningBitArray(ctx sdk.Context, address sdk.Address
 	store.Set(GetValidatorSigningBitArrayKey(address, index), bz)
 }
 
+// Construct a new `ValidatorSigningInfo` struct
+func NewValidatorSigningInfo(startHeight int64, indexOffset int64, jailedUntil int64, signedBlocksCounter int64) ValidatorSigningInfo {
+	return ValidatorSigningInfo{
+		StartHeight:         startHeight,
+		IndexOffset:         indexOffset,
+		JailedUntil:         jailedUntil,
+		SignedBlocksCounter: signedBlocksCounter,
+	}
+}
+
 // Signing info for a validator
 type ValidatorSigningInfo struct {
 	StartHeight         int64 `json:"start_height"`          // height at which validator was first a candidate OR was unrevoked
diff --git a/x/stake/app_test.go b/x/stake/app_test.go
index 8e20633a0..940d4db2b 100644
--- a/x/stake/app_test.go
+++ b/x/stake/app_test.go
@@ -117,7 +117,7 @@ func TestStakeMsgs(t *testing.T) {
 	createValidatorMsg := NewMsgCreateValidator(
 		addr1, priv1.PubKey(), bondCoin, description,
 	)
-	mock.SignCheckDeliver(t, mapp.BaseApp, createValidatorMsg, []int64{0}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, createValidatorMsg, []int64{0}, []int64{0}, true, priv1)
 	mock.CheckBalance(t, mapp, addr1, sdk.Coins{genCoin.Minus(bondCoin)})
 	mapp.BeginBlock(abci.RequestBeginBlock{})
 
@@ -134,7 +134,7 @@ func TestStakeMsgs(t *testing.T) {
 
 	description = NewDescription("bar_moniker", "", "", "")
 	editValidatorMsg := NewMsgEditValidator(addr1, description)
-	mock.SignCheckDeliver(t, mapp.BaseApp, editValidatorMsg, []int64{1}, true, priv1)
+	mock.SignCheckDeliver(t, mapp.BaseApp, editValidatorMsg, []int64{0}, []int64{1}, true, priv1)
 	validator = checkValidator(t, mapp, keeper, addr1, true)
 	require.Equal(t, description, validator.Description)
 
@@ -143,7 +143,7 @@ func TestStakeMsgs(t *testing.T) {
 
 	mock.CheckBalance(t, mapp, addr2, sdk.Coins{genCoin})
 	delegateMsg := NewMsgDelegate(addr2, addr1, bondCoin)
-	mock.SignCheckDeliver(t, mapp.BaseApp, delegateMsg, []int64{0}, true, priv2)
+	mock.SignCheckDeliver(t, mapp.BaseApp, delegateMsg, []int64{1}, []int64{0}, true, priv2)
 	mock.CheckBalance(t, mapp, addr2, sdk.Coins{genCoin.Minus(bondCoin)})
 	checkDelegation(t, mapp, keeper, addr2, addr1, true, sdk.NewRat(10))
 
@@ -151,7 +151,7 @@ func TestStakeMsgs(t *testing.T) {
 	// Unbond
 
 	unbondMsg := NewMsgUnbond(addr2, addr1, "MAX")
-	mock.SignCheckDeliver(t, mapp.BaseApp, unbondMsg, []int64{1}, true, priv2)
+	mock.SignCheckDeliver(t, mapp.BaseApp, unbondMsg, []int64{1}, []int64{1}, true, priv2)
 	mock.CheckBalance(t, mapp, addr2, sdk.Coins{genCoin})
 	checkDelegation(t, mapp, keeper, addr2, addr1, false, sdk.Rat{})
 }
diff --git a/x/stake/client/rest/tx.go b/x/stake/client/rest/tx.go
index 19eca4c44..77a6540ee 100644
--- a/x/stake/client/rest/tx.go
+++ b/x/stake/client/rest/tx.go
@@ -39,6 +39,7 @@ type editDelegationsBody struct {
 	LocalAccountName string             `json:"name"`
 	Password         string             `json:"password"`
 	ChainID          string             `json:"chain_id"`
+	AccountNumber    int64              `json:"account_number"`
 	Sequence         int64              `json:"sequence"`
 	Gas              int64              `json:"gas"`
 	Delegate         []msgDelegateInput `json:"delegate"`
@@ -129,6 +130,7 @@ func editDelegationsRequestHandlerFn(cdc *wire.Codec, kb keys.Keybase, ctx conte
 		signedTxs := make([][]byte, len(messages[:]))
 		for i, msg := range messages {
 			// increment sequence for each message
+			ctx = ctx.WithAccountNumber(m.AccountNumber)
 			ctx = ctx.WithSequence(m.Sequence)
 			m.Sequence++