diff --git a/app/app_test.go b/app/app_test.go
index 3936359ab..e2c418dfe 100644
--- a/app/app_test.go
+++ b/app/app_test.go
@@ -25,7 +25,7 @@ type testTx struct {
 func (tx testTx) Get(key interface{}) (value interface{}) { return nil }
 func (tx testTx) SignBytes() []byte                       { return nil }
 func (tx testTx) ValidateBasic() error                    { return nil }
-func (tx testTx) Signers() []types.Address                { return nil }
+func (tx testTx) Signers() []crypto.Address               { return nil }
 func (tx testTx) TxBytes() []byte                         { return nil }
 func (tx testTx) Signatures() []types.StdSignature        { return nil }
 
diff --git a/examples/basecoin/account.go b/examples/basecoin/account.go
deleted file mode 100644
index 7985b3eb1..000000000
--- a/examples/basecoin/account.go
+++ /dev/null
@@ -1,71 +0,0 @@
-package main
-
-import (
-	"github.com/cosmos/cosmos-sdk/types"
-	crypto "github.com/tendermint/go-crypto"
-)
-
-// AppAccount - coin account structure
-type AppAccount struct {
-	Address_ crypto.Address `json:"address"`
-	Coins    types.Coins    `json:"coins"`
-	PubKey_  crypto.PubKey  `json:"public_key"` // can't conflict with PubKey()
-	Sequence int64          `json:"sequence"`
-}
-
-// Implements auth.Account
-func (a *AppAccount) Get(key interface{}) (value interface{}, err error) {
-	switch key.(type) {
-	case string:
-		//
-	default:
-		panic("HURAH!")
-	}
-	return nil, nil
-}
-
-// Implements auth.Account
-func (a *AppAccount) Set(key interface{}, value interface{}) error {
-	switch key.(type) {
-	case string:
-		//
-	default:
-		panic("HURAH!")
-	}
-	return nil
-}
-
-// Implements auth.Account
-func (a *AppAccount) Address() types.Address {
-	return a.PubKey_.Address()
-}
-
-// Implements auth.Account
-func (a *AppAccount) PubKey() crypto.PubKey {
-	return a.PubKey_
-}
-
-func (a *AppAccount) SetPubKey(pubKey crypto.PubKey) error {
-	a.PubKey_ = pubKey
-	return nil
-}
-
-// Implements coinstore.Coinser
-func (a *AppAccount) GetCoins() types.Coins {
-	return a.Coins
-}
-
-// Implements coinstore.Coinser
-func (a *AppAccount) SetCoins(coins types.Coins) error {
-	a.Coins = coins
-	return nil
-}
-
-func (a *AppAccount) GetSequence() int64 {
-	return a.Sequence
-}
-
-func (a *AppAccount) SetSequence(seq int64) error {
-	a.Sequence = seq
-	return nil
-}
diff --git a/examples/basecoin/account_store.go b/examples/basecoin/account_store.go
deleted file mode 100644
index 53078ff6b..000000000
--- a/examples/basecoin/account_store.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"path"
-
-	"github.com/cosmos/cosmos-sdk/types"
-)
-
-type AppAccountStore struct {
-	kvStore types.KVStore
-}
-
-func newAccountStore(kvStore types.KVStore) types.AccountStore {
-	return AppAccountStore{kvStore}
-}
-
-func (accStore AppAccountStore) NewAccountWithAddress(addr types.Address) types.Account {
-	return &AppAccount{
-		Address_: addr,
-	}
-}
-
-func (accStore AppAccountStore) GetAccount(addr types.Address) types.Account {
-	v := accStore.kvStore.Get(keyAccount(addr))
-
-	if len(v) == 0 {
-		return nil
-	}
-
-	acc := new(AppAccount)
-	if err := json.Unmarshal(v, acc); err != nil {
-		panic(err)
-	}
-
-	return acc
-}
-
-func (accStore AppAccountStore) SetAccount(acc types.Account) {
-	b, err := json.Marshal(acc)
-	if err != nil {
-		panic(err)
-	}
-
-	appAcc, ok := acc.(*AppAccount)
-	if !ok {
-		panic("acc is not *AppAccount") // XXX
-	}
-
-	accStore.kvStore.Set(keyAccount(appAcc.Address_), b)
-}
-
-func keyAccount(addr types.Address) []byte {
-	return []byte(path.Join("account", string(addr)))
-}
diff --git a/examples/basecoin/app.go b/examples/basecoin/app.go
new file mode 100644
index 000000000..e1181d041
--- /dev/null
+++ b/examples/basecoin/app.go
@@ -0,0 +1,66 @@
+package main
+
+import (
+	"encoding/json"
+	"path"
+
+	crypto "github.com/tendermint/go-crypto"
+
+	"github.com/cosmos/cosmos-sdk/types"
+	acm "github.com/cosmos/cosmos-sdk/x/account"
+	"github.com/cosmos/cosmos-sdk/x/sendtx"
+	"github.com/cosmos/cosmos-sdk/x/store"
+)
+
+func txParser(txBytes []byte) (types.Tx, error) {
+	var tx sendtx.SendTx
+	err := json.Unmarshal(txBytes, &tx)
+	return tx, err
+}
+
+//-----------------------------------------------------------------------------
+
+type AccountStore struct {
+	kvStore types.KVStore
+}
+
+func newAccountStore(kvStore types.KVStore) store.AccountStore {
+	return AccountStore{kvStore}
+}
+
+func (accStore AccountStore) NewAccountWithAddress(addr crypto.Address) store.Account {
+	return acm.NewBaseAccountWithAddress(addr)
+}
+
+func (accStore AccountStore) GetAccount(addr crypto.Address) store.Account {
+	v := accStore.kvStore.Get(keyAccount(addr))
+
+	if len(v) == 0 {
+		return nil
+	}
+
+	acc := new(acm.BaseAccount)
+	if err := json.Unmarshal(v, acc); err != nil {
+		panic(err)
+	}
+
+	return acc
+}
+
+func (accStore AccountStore) SetAccount(acc store.Account) {
+	b, err := json.Marshal(acc)
+	if err != nil {
+		panic(err)
+	}
+
+	appAcc, ok := acc.(*acm.BaseAccount)
+	if !ok {
+		panic("acc is not *acm.BaseAccount") // XXX
+	}
+
+	accStore.kvStore.Set(keyAccount(appAcc.Address()), b)
+}
+
+func keyAccount(addr crypto.Address) []byte {
+	return []byte(path.Join("account", string(addr)))
+}
diff --git a/examples/basecoin/main.go b/examples/basecoin/main.go
index 96e1bd43c..149f4a6dd 100644
--- a/examples/basecoin/main.go
+++ b/examples/basecoin/main.go
@@ -1,7 +1,6 @@
 package main
 
 import (
-	"encoding/json"
 	"fmt"
 	"os"
 
@@ -73,11 +72,3 @@ func main() {
 	})
 	return
 }
-
-// create ctx in begin block to be used as background for txs ...
-
-func txParser(txBytes []byte) (types.Tx, error) {
-	var tx sendtx.SendTx
-	err := json.Unmarshal(txBytes, &tx)
-	return tx, err
-}
diff --git a/examples/dummy/main.go b/examples/dummy/main.go
index ea478f066..dfacafa92 100644
--- a/examples/dummy/main.go
+++ b/examples/dummy/main.go
@@ -6,6 +6,7 @@ import (
 	"os"
 
 	"github.com/tendermint/abci/server"
+	crypto "github.com/tendermint/go-crypto"
 	cmn "github.com/tendermint/tmlibs/common"
 	dbm "github.com/tendermint/tmlibs/db"
 
@@ -89,7 +90,7 @@ func (tx dummyTx) ValidateBasic() error {
 	return nil
 }
 
-func (tx dummyTx) Signers() []types.Address {
+func (tx dummyTx) Signers() []crypto.Address {
 	return nil
 }
 
diff --git a/types/_gen.go b/types/_gen.go
deleted file mode 100644
index a98feaf4e..000000000
--- a/types/_gen.go
+++ /dev/null
@@ -1,6 +0,0 @@
-package main
-
-import (
-	_ "github.com/tendermint/go-wire/gen"
-	_ "github.com/clipperhouse/stringer"
-)
diff --git a/types/account.go b/types/account.go
deleted file mode 100644
index f25bc1d48..000000000
--- a/types/account.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package types
-
-import (
-	crypto "github.com/tendermint/go-crypto"
-)
-
-type Address = crypto.Address
-
-type Account interface {
-	Address() Address
-
-	PubKey() crypto.PubKey
-	SetPubKey(crypto.PubKey) error
-
-	GetCoins() Coins
-	SetCoins(Coins) error
-
-	GetSequence() int64
-	SetSequence(int64) error
-
-	Get(key interface{}) (value interface{}, err error)
-	Set(key interface{}, value interface{}) error
-}
-
-type AccountStore interface {
-	NewAccountWithAddress(addr Address) Account
-	GetAccount(addr Address) Account
-	SetAccount(acc Account)
-}
diff --git a/types/tx_msg.go b/types/tx_msg.go
index 2d432f845..b6d35d137 100644
--- a/types/tx_msg.go
+++ b/types/tx_msg.go
@@ -1,5 +1,7 @@
 package types
 
+import crypto "github.com/tendermint/go-crypto"
+
 type Msg interface {
 
 	// Get some property of the Msg.
@@ -15,7 +17,7 @@ type Msg interface {
 	// Signers returns the addrs of signers that must sign.
 	// CONTRACT: All signatures must be present to be valid.
 	// CONTRACT: Returns addrs in some deterministic order.
-	Signers() []Address
+	Signers() []crypto.Address
 }
 
 type Tx interface {
diff --git a/x/account/account.go b/x/account/account.go
new file mode 100644
index 000000000..980945220
--- /dev/null
+++ b/x/account/account.go
@@ -0,0 +1,113 @@
+package account
+
+import (
+	"encoding/json"
+
+	crypto "github.com/tendermint/go-crypto"
+
+	"github.com/cosmos/cosmos-sdk/x/coin"
+)
+
+//-----------------------------------------------------------
+// BaseAccount
+
+// BaseAccount - coin account structure
+type BaseAccount struct {
+	address  crypto.Address
+	coins    coin.Coins
+	pubKey   crypto.PubKey
+	sequence int64
+}
+
+func NewBaseAccountWithAddress(addr crypto.Address) *BaseAccount {
+	return &BaseAccount{
+		address: addr,
+	}
+}
+
+// BaseAccountWire is the account structure used for serialization
+type BaseAccountWire struct {
+	Address  crypto.Address `json:"address"`
+	Coins    coin.Coins     `json:"coins"`
+	PubKey   crypto.PubKey  `json:"public_key"` // can't conflict with PubKey()
+	Sequence int64          `json:"sequence"`
+}
+
+func (acc *BaseAccount) MarshalJSON() ([]byte, error) {
+	return json.Marshal(BaseAccountWire{
+		Address:  acc.address,
+		Coins:    acc.coins,
+		PubKey:   acc.pubKey,
+		Sequence: acc.sequence,
+	})
+}
+
+func (acc *BaseAccount) UnmarshalJSON(bz []byte) error {
+	accWire := new(BaseAccountWire)
+	err := json.Unmarshal(bz, accWire)
+	if err != nil {
+		return err
+	}
+	acc.address = accWire.Address
+	acc.coins = accWire.Coins
+	acc.pubKey = accWire.PubKey
+	acc.sequence = accWire.Sequence
+	return nil
+}
+
+// Implements Account
+func (acc *BaseAccount) Get(key interface{}) (value interface{}, err error) {
+	switch key.(type) {
+	case string:
+		//
+	default:
+		panic("HURAH!")
+	}
+	return nil, nil
+}
+
+// Implements Account
+func (acc *BaseAccount) Set(key interface{}, value interface{}) error {
+	switch key.(type) {
+	case string:
+		//
+	default:
+		panic("HURAH!")
+	}
+	return nil
+}
+
+// Implements Account
+func (acc *BaseAccount) Address() crypto.Address {
+	return acc.pubKey.Address()
+}
+
+// Implements Account
+func (acc *BaseAccount) GetPubKey() crypto.PubKey {
+	return acc.pubKey
+}
+
+func (acc *BaseAccount) SetPubKey(pubKey crypto.PubKey) error {
+	acc.pubKey = pubKey
+	return nil
+}
+
+// Implements coinstore.Coinser
+func (acc *BaseAccount) GetCoins() coin.Coins {
+	return acc.coins
+}
+
+// Implements coinstore.Coinser
+func (acc *BaseAccount) SetCoins(coins coin.Coins) error {
+	acc.coins = coins
+	return nil
+}
+
+func (acc *BaseAccount) GetSequence() int64 {
+	return acc.sequence
+}
+
+func (acc *BaseAccount) SetSequence(seq int64) error {
+	acc.sequence = seq
+	return nil
+}
diff --git a/x/auth/context.go b/x/auth/context.go
index 07e86b7d6..43c182a23 100644
--- a/x/auth/context.go
+++ b/x/auth/context.go
@@ -2,6 +2,7 @@ package auth
 
 import (
 	"github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/store"
 )
 
 /*
@@ -24,10 +25,10 @@ const (
 	contextKeyAccount contextKey = iota
 )
 
-func SetAccount(ctx types.Context, account types.Account) types.Context {
+func SetAccount(ctx types.Context, account store.Account) types.Context {
 	return ctx.WithValueUnsafe(contextKeyAccount, account)
 }
 
-func GetAccount(ctx types.Context) types.Account {
-	return ctx.Value(contextKeyAccount).(types.Account)
+func GetAccount(ctx types.Context) store.Account {
+	return ctx.Value(contextKeyAccount).(store.Account)
 }
diff --git a/x/auth/decorator.go b/x/auth/decorator.go
index 38311563f..5bd443368 100644
--- a/x/auth/decorator.go
+++ b/x/auth/decorator.go
@@ -2,15 +2,14 @@ package auth
 
 import (
 	"github.com/cosmos/cosmos-sdk/types"
-	crypto "github.com/tendermint/go-crypto"
+	"github.com/cosmos/cosmos-sdk/x/store"
 )
 
-func DecoratorFn(newAccountStore func(types.KVStore) types.AccountStore) types.Decorator {
+func DecoratorFn(newAccountStore func(types.KVStore) store.AccountStore) types.Decorator {
 	return func(ctx types.Context, ms types.MultiStore, tx types.Tx, next types.Handler) types.Result {
 
 		accountStore := newAccountStore(ms.GetKVStore("main"))
 
-		// NOTE: we actually dont need Signers() since we have pubkeys in Signatures()
 		signers := tx.Signers()
 		signatures := tx.Signatures()
 
@@ -68,11 +67,3 @@ func DecoratorFn(newAccountStore func(types.KVStore) types.AccountStore) types.D
 		return next(ctx, ms, tx)
 	}
 }
-
-type Auther interface {
-	GetPubKey() crypto.PubKey
-	SetPubKey(crypto.PubKey) error
-
-	GetSequence() int64
-	SetSequence() (int64, error)
-}
diff --git a/x/auth/types.go b/x/auth/types.go
index 5f62fa5d3..aaa8018cf 100644
--- a/x/auth/types.go
+++ b/x/auth/types.go
@@ -1,9 +1,16 @@
 package auth
 
 import (
+	"github.com/cosmos/cosmos-sdk/x/store"
 	crypto "github.com/tendermint/go-crypto"
 )
 
-type SetPubKeyer interface {
-	SetPubKey(crypto.PubKey)
+var _ Auther = (store.Account)(nil)
+
+type Auther interface {
+	GetPubKey() crypto.PubKey
+	SetPubKey(crypto.PubKey) error
+
+	GetSequence() int64
+	SetSequence(int64) error
 }
diff --git a/x/coinstore/_attic/bench_test.go b/x/coin/_attic/bench_test.go
similarity index 100%
rename from x/coinstore/_attic/bench_test.go
rename to x/coin/_attic/bench_test.go
diff --git a/x/coinstore/_attic/commands/query.go b/x/coin/_attic/commands/query.go
similarity index 100%
rename from x/coinstore/_attic/commands/query.go
rename to x/coin/_attic/commands/query.go
diff --git a/x/coinstore/_attic/commands/tx.go b/x/coin/_attic/commands/tx.go
similarity index 100%
rename from x/coinstore/_attic/commands/tx.go
rename to x/coin/_attic/commands/tx.go
diff --git a/x/coinstore/_attic/genesis.go b/x/coin/_attic/genesis.go
similarity index 100%
rename from x/coinstore/_attic/genesis.go
rename to x/coin/_attic/genesis.go
diff --git a/x/coinstore/_attic/handler.go b/x/coin/_attic/handler.go
similarity index 100%
rename from x/coinstore/_attic/handler.go
rename to x/coin/_attic/handler.go
diff --git a/x/coinstore/_attic/handler_test.go b/x/coin/_attic/handler_test.go
similarity index 100%
rename from x/coinstore/_attic/handler_test.go
rename to x/coin/_attic/handler_test.go
diff --git a/x/coinstore/_attic/helper.go b/x/coin/_attic/helper.go
similarity index 100%
rename from x/coinstore/_attic/helper.go
rename to x/coin/_attic/helper.go
diff --git a/x/coinstore/_attic/ibc_test.go b/x/coin/_attic/ibc_test.go
similarity index 100%
rename from x/coinstore/_attic/ibc_test.go
rename to x/coin/_attic/ibc_test.go
diff --git a/x/coinstore/_attic/rest/handlers.go b/x/coin/_attic/rest/handlers.go
similarity index 100%
rename from x/coinstore/_attic/rest/handlers.go
rename to x/coin/_attic/rest/handlers.go
diff --git a/x/coinstore/_attic/store.go b/x/coin/_attic/store.go
similarity index 100%
rename from x/coinstore/_attic/store.go
rename to x/coin/_attic/store.go
diff --git a/types/coin.go b/x/coin/coin.go
similarity index 97%
rename from types/coin.go
rename to x/coin/coin.go
index 2c525b26d..99ffc553d 100644
--- a/types/coin.go
+++ b/x/coin/coin.go
@@ -1,4 +1,4 @@
-package types
+package coin
 
 import (
 	"fmt"
@@ -202,14 +202,6 @@ var _ sort.Interface = Coins{}
 // Sort is a helper function to sort the set of coins inplace
 func (coins Coins) Sort() { sort.Sort(coins) }
 
-//----------------------------------------
-// Misc
-
-type Coinser interface {
-	GetCoins() Coins
-	SetCoins(Coins)
-}
-
 //----------------------------------------
 // Parsing
 
diff --git a/types/coin_test.go b/x/coin/coin_test.go
similarity index 99%
rename from types/coin_test.go
rename to x/coin/coin_test.go
index bf651c50d..0cb2b4f21 100644
--- a/types/coin_test.go
+++ b/x/coin/coin_test.go
@@ -1,4 +1,4 @@
-package types
+package coin
 
 import (
 	"testing"
diff --git a/x/coinstore/store.go b/x/coinstore/store.go
deleted file mode 100644
index 7ee4467c3..000000000
--- a/x/coinstore/store.go
+++ /dev/null
@@ -1,117 +0,0 @@
-package coin
-
-import (
-	"fmt"
-
-	"github.com/cosmos/cosmos-sdk/types"
-)
-
-type Coins = types.Coins
-
-type Coinser interface {
-	GetCoins() Coins
-	SetCoins(Coins)
-}
-
-// CoinStore manages transfers between accounts
-type CoinStore struct {
-	types.AccountStore
-}
-
-// get the account as a Coinser. if the account doesn't exist, return nil.
-// if it's not a Coinser, return error.
-func (cs CoinStore) getCoinserAccount(addr types.Address) (types.Coinser, error) {
-	_acc := cs.GetAccount(addr)
-	if _acc == nil {
-		return nil, nil
-	}
-
-	acc, ok := _acc.(Coinser)
-	if !ok {
-		return nil, fmt.Errorf("Account %s is not a Coinser", addr)
-	}
-	return acc, nil
-}
-
-func (cs CoinStore) SubtractCoins(addr types.Address, amt Coins) (Coins, error) {
-	acc, err := cs.getCoinserAccount(addr)
-	if err != nil {
-		return amt, err
-	} else if acc == nil {
-		return amt, fmt.Errorf("Sending account (%s) does not exist", addr)
-	}
-
-	coins := acc.GetCoins()
-	newCoins := coins.Minus(amt)
-	if !newCoins.IsNotNegative() {
-		return amt, ErrInsufficientCoins(fmt.Sprintf("%s < %s", coins, amt))
-	}
-
-	acc.SetCoins(newCoins)
-	cs.SetAccount(acc.(types.Account))
-	return newCoins, nil
-}
-
-func (cs CoinStore) AddCoins(addr types.Address, amt Coins) (Coins, error) {
-	acc, err := cs.getCoinserAccount(addr)
-	if err != nil {
-		return amt, err
-	} else if acc == nil {
-		acc = cs.AccountStore.NewAccountWithAddress(addr).(Coinser)
-	}
-
-	coins := acc.GetCoins()
-	newCoins := coins.Plus(amt)
-
-	acc.SetCoins(newCoins)
-	cs.SetAccount(acc.(types.Account))
-	return newCoins, nil
-}
-
-/*
-// TransferCoins transfers coins from fromAddr to toAddr.
-// It returns an error if the from account doesn't exist,
-// if the accounts doin't implement Coinser,
-// or if the from account does not have enough coins.
-func (cs CoinStore) TransferCoins(fromAddr, toAddr types.Address, amt Coins) error {
-	var fromAcc, toAcc types.Account
-
-	// Get the accounts
-	_fromAcc := cs.GetAccount(fromAddr)
-	if _fromAcc == nil {
-		return ErrUnknownAccount(fromAddr)
-	}
-
-	_toAcc := cs.GetAccount(to)
-	if _toAcc == nil {
-		toAcc = cs.AccountStore.NewAccountWithAddress(to)
-	}
-
-	// Ensure they are Coinser
-	fromAcc, ok := _fromAcc.(Coinser)
-	if !ok {
-		return ErrAccountNotCoinser(from)
-	}
-
-	toAcc, ok = _toAcc.(Coinser)
-	if !ok {
-		return ErrAccountNotCoinser(from)
-	}
-
-	// Coin math
-	fromCoins := fromAcc.GetCoins()
-	newFromCoins := fromCoins.Minus(amt)
-	if newFromCoins.Negative() {
-		return ErrInsufficientCoins(fromCoins, amt)
-	}
-	toCoins := toAcc.GetCoins()
-	newToCoins := toCoins.Plus(amt)
-
-	// Set everything!
-	fromAcc.SetCoins(newFromCoins)
-	toAcc.SetCoins(newToCoins)
-	cs.SetAccount(fromAcc)
-	cs.SetAccount(toAcc)
-
-	return nil
-}*/
diff --git a/x/sendtx/handler.go b/x/sendtx/handler.go
index fcbb66a00..fba7a5a3c 100644
--- a/x/sendtx/handler.go
+++ b/x/sendtx/handler.go
@@ -2,14 +2,14 @@ package sendtx
 
 import (
 	"github.com/cosmos/cosmos-sdk/types"
-	coinstore "github.com/cosmos/cosmos-sdk/x/coinstore"
+	"github.com/cosmos/cosmos-sdk/x/store"
 )
 
-func TransferHandlerFn(newAccStore func(types.KVStore) types.AccountStore) types.Handler {
+func TransferHandlerFn(newAccStore func(types.KVStore) store.AccountStore) types.Handler {
 	return func(ctx types.Context, ms types.MultiStore, tx types.Tx) types.Result {
 
 		accStore := newAccStore(ms.GetKVStore("main"))
-		cs := coinstore.CoinStore{accStore}
+		cs := store.CoinStore{accStore}
 
 		sendTx, ok := tx.(SendTx)
 		if !ok {
diff --git a/x/sendtx/tx.go b/x/sendtx/tx.go
index 839eaa3be..664507a0f 100644
--- a/x/sendtx/tx.go
+++ b/x/sendtx/tx.go
@@ -4,14 +4,16 @@ import (
 	"encoding/json"
 	"fmt"
 
-	"github.com/cosmos/cosmos-sdk/types"
-	coinstore "github.com/cosmos/cosmos-sdk/x/coinstore"
 	crypto "github.com/tendermint/go-crypto"
+
+	"github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/coin"
+	"github.com/cosmos/cosmos-sdk/x/store"
 )
 
 type (
-	Address = types.Address
-	Coins   = types.Coins
+	Address = crypto.Address
+	Coins   = coin.Coins
 )
 
 //-----------------------------------------------------------------------------
@@ -28,16 +30,16 @@ type TxInput struct {
 // ValidateBasic - validate transaction input
 func (txIn TxInput) ValidateBasic() error {
 	if len(txIn.Address) == 0 {
-		return coinstore.ErrInvalidAddress(txIn.Address.String())
+		return store.ErrInvalidAddress(txIn.Address.String())
 	}
 	if txIn.Sequence < 0 {
 		return ErrInvalidSequence(txIn.Sequence)
 	}
 	if !txIn.Coins.IsValid() {
-		return coinstore.ErrInvalidCoins(txIn.Coins.String())
+		return store.ErrInvalidCoins(txIn.Coins.String())
 	}
 	if !txIn.Coins.IsPositive() {
-		return coinstore.ErrInvalidCoins(txIn.Coins.String())
+		return store.ErrInvalidCoins(txIn.Coins.String())
 	}
 	return nil
 }
@@ -66,13 +68,13 @@ type TxOutput struct {
 // ValidateBasic - validate transaction output
 func (txOut TxOutput) ValidateBasic() error {
 	if len(txOut.Address) == 0 {
-		return coinstore.ErrInvalidAddress(txOut.Address.String())
+		return store.ErrInvalidAddress(txOut.Address.String())
 	}
 	if !txOut.Coins.IsValid() {
-		return coinstore.ErrInvalidCoins(txOut.Coins.String())
+		return store.ErrInvalidCoins(txOut.Coins.String())
 	}
 	if !txOut.Coins.IsPositive() {
-		return coinstore.ErrInvalidCoins(txOut.Coins.String())
+		return store.ErrInvalidCoins(txOut.Coins.String())
 	}
 	return nil
 }
@@ -92,28 +94,14 @@ func NewTxOutput(addr Address, coins Coins) TxOutput {
 
 //-----------------------------------------------------------------------------
 
+var _ types.Tx = (*SendTx)(nil)
+
 // SendTx - high level transaction of the coin module
-// Satisfies: TxInner
 type SendTx struct {
 	Inputs  []TxInput  `json:"inputs"`
 	Outputs []TxOutput `json:"outputs"`
 }
 
-var _ types.Tx = (*SendTx)(nil)
-
-// NewSendTx - construct arbitrary multi-in, multi-out sendtx
-func NewSendTx(in []TxInput, out []TxOutput) types.Tx {
-	return SendTx{Inputs: in, Outputs: out}
-}
-
-// NewSendOneTx is a helper for the standard (?) case where there is exactly
-// one sender and one recipient
-func NewSendOneTx(sender, recipient types.Address, amount types.Coins) types.Tx {
-	in := []TxInput{{Address: sender, Coins: amount}}
-	out := []TxOutput{{Address: recipient, Coins: amount}}
-	return SendTx{Inputs: in, Outputs: out}
-}
-
 // ValidateBasic - validate the send transaction
 func (tx SendTx) ValidateBasic() error {
 	// this just makes sure all the inputs and outputs are properly formatted,
@@ -140,7 +128,7 @@ func (tx SendTx) ValidateBasic() error {
 	}
 	// make sure inputs and outputs match
 	if !totalIn.IsEqual(totalOut) {
-		return coinstore.ErrInvalidCoins(totalIn.String()) // TODO
+		return store.ErrInvalidCoins(totalIn.String()) // TODO
 	}
 	return nil
 }
@@ -149,8 +137,22 @@ func (tx SendTx) String() string {
 	return fmt.Sprintf("SendTx{%v->%v}", tx.Inputs, tx.Outputs)
 }
 
-// TODO
+// NewSendTx - construct arbitrary multi-in, multi-out sendtx
+func NewSendTx(in []TxInput, out []TxOutput) types.Tx {
+	return SendTx{Inputs: in, Outputs: out}
+}
+
+// NewSendOneTx is a helper for the standard (?) case where there is exactly
+// one sender and one recipient
+func NewSendOneTx(sender, recipient crypto.Address, amount coin.Coins) types.Tx {
+	in := []TxInput{{Address: sender, Coins: amount}}
+	out := []TxOutput{{Address: recipient, Coins: amount}}
+	return SendTx{Inputs: in, Outputs: out}
+}
+
 //------------------------
+// Implements types.Tx
+
 func (tx SendTx) Get(key interface{}) (value interface{}) {
 	switch k := key.(type) {
 	case string:
@@ -170,8 +172,8 @@ func (tx SendTx) SignBytes() []byte {
 	return b
 }
 
-func (tx SendTx) Signers() []types.Address {
-	addrs := make([]types.Address, len(tx.Inputs))
+func (tx SendTx) Signers() []crypto.Address {
+	addrs := make([]crypto.Address, len(tx.Inputs))
 	for i, in := range tx.Inputs {
 		addrs[i] = in.Address
 	}
diff --git a/x/store/account.go b/x/store/account.go
new file mode 100644
index 000000000..456530170
--- /dev/null
+++ b/x/store/account.go
@@ -0,0 +1,34 @@
+package store
+
+import (
+	crypto "github.com/tendermint/go-crypto"
+
+	"github.com/cosmos/cosmos-sdk/x/coin"
+)
+
+// AccountStore indexes accounts by address.
+type AccountStore interface {
+	NewAccountWithAddress(addr crypto.Address) Account
+	GetAccount(addr crypto.Address) Account
+	SetAccount(acc Account)
+}
+
+// Account is a standard balance account
+// using a sequence number for replay protection
+// and a single pubkey for authentication.
+// TODO: multisig accounts?
+type Account interface {
+	Address() crypto.Address
+
+	GetPubKey() crypto.PubKey
+	SetPubKey(crypto.PubKey) error
+
+	GetCoins() coin.Coins
+	SetCoins(coin.Coins) error
+
+	GetSequence() int64
+	SetSequence(int64) error
+
+	Get(key interface{}) (value interface{}, err error)
+	Set(key interface{}, value interface{}) error
+}
diff --git a/x/store/coin.go b/x/store/coin.go
new file mode 100644
index 000000000..8626b235d
--- /dev/null
+++ b/x/store/coin.go
@@ -0,0 +1,73 @@
+package store
+
+import (
+	"fmt"
+
+	"github.com/cosmos/cosmos-sdk/x/coin"
+	crypto "github.com/tendermint/go-crypto"
+)
+
+type Coins = coin.Coins
+
+// Coinser can get and set coins
+type Coinser interface {
+	GetCoins() Coins
+	SetCoins(Coins)
+}
+
+// CoinStore manages transfers between accounts
+type CoinStore struct {
+	AccountStore
+}
+
+// SubtractCoins subtracts amt from the coins at the addr.
+func (cs CoinStore) SubtractCoins(addr crypto.Address, amt Coins) (Coins, error) {
+	acc, err := cs.getCoinserAccount(addr)
+	if err != nil {
+		return amt, err
+	} else if acc == nil {
+		return amt, fmt.Errorf("Sending account (%s) does not exist", addr)
+	}
+
+	coins := acc.GetCoins()
+	newCoins := coins.Minus(amt)
+	if !newCoins.IsNotNegative() {
+		return amt, ErrInsufficientCoins(fmt.Sprintf("%s < %s", coins, amt))
+	}
+
+	acc.SetCoins(newCoins)
+	cs.SetAccount(acc.(Account))
+	return newCoins, nil
+}
+
+// AddCoins adds amt to the coins at the addr.
+func (cs CoinStore) AddCoins(addr crypto.Address, amt Coins) (Coins, error) {
+	acc, err := cs.getCoinserAccount(addr)
+	if err != nil {
+		return amt, err
+	} else if acc == nil {
+		acc = cs.AccountStore.NewAccountWithAddress(addr).(Coinser)
+	}
+
+	coins := acc.GetCoins()
+	newCoins := coins.Plus(amt)
+
+	acc.SetCoins(newCoins)
+	cs.SetAccount(acc.(Account))
+	return newCoins, nil
+}
+
+// get the account as a Coinser. if the account doesn't exist, return nil.
+// if it's not a Coinser, return error.
+func (cs CoinStore) getCoinserAccount(addr crypto.Address) (Coinser, error) {
+	_acc := cs.GetAccount(addr)
+	if _acc == nil {
+		return nil, nil
+	}
+
+	acc, ok := _acc.(Coinser)
+	if !ok {
+		return nil, fmt.Errorf("Account %s is not a Coinser", addr)
+	}
+	return acc, nil
+}
diff --git a/x/coinstore/errors.go b/x/store/errors.go
similarity index 99%
rename from x/coinstore/errors.go
rename to x/store/errors.go
index a8fce42ac..bcdb3d3f0 100644
--- a/x/coinstore/errors.go
+++ b/x/store/errors.go
@@ -1,5 +1,5 @@
 //nolint
-package coin
+package store
 
 import (
 	"github.com/cosmos/cosmos-sdk/errors"