diff --git a/lib/model/wallet.js b/lib/model/wallet.js
index 99d5667..e3baf21 100644
--- a/lib/model/wallet.js
+++ b/lib/model/wallet.js
@@ -27,6 +27,7 @@ Wallet.create = function(opts) {
   x.name = opts.name;
   x.m = opts.m;
   x.n = opts.n;
+  x.singleAddress = !!opts.singleAddress;
   x.status = 'pending';
   x.publicKeyRing = [];
   x.addressIndex = 0;
@@ -56,6 +57,7 @@ Wallet.fromObj = function(obj) {
   x.name = obj.name;
   x.m = obj.m;
   x.n = obj.n;
+  x.singleAddress = !!obj.singleAddress;
   x.status = obj.status;
   x.publicKeyRing = obj.publicKeyRing;
   x.copayers = _.map(obj.copayers, function(copayer) {
diff --git a/lib/server.js b/lib/server.js
index 8c3ccd2..c3bade5 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -62,7 +62,8 @@ function WalletService() {
 function checkRequired(obj, args, cb) {
   var missing = Utils.getMissingFields(obj, args);
   if (_.isEmpty(missing)) return true;
-  cb(new ClientError('Required argument ' + _.first(missing) + ' missing.'));
+  if (_.isFunction(cb))
+    cb(new ClientError('Required argument ' + _.first(missing) + ' missing.'));
   return false;
 };
 
@@ -215,8 +216,9 @@ WalletService.prototype._runLocked = function(cb, task) {
  * @param {number} opts.m - Required copayers.
  * @param {number} opts.n - Total copayers.
  * @param {string} opts.pubKey - Public key to verify copayers joining have access to the wallet secret.
- * @param {string} [opts.network = 'livenet'] - The Bitcoin network for this wallet.
- * @param {string} [opts.supportBIP44AndP2PKH = true] - Client supports BIP44 & P2PKH for new wallets.
+ * @param {string} opts.singleAddress[=false] - The wallet will only ever have one address.
+ * @param {string} opts.network[='livenet'] - The Bitcoin network for this wallet.
+ * @param {string} opts.supportBIP44AndP2PKH[=true] - Client supports BIP44 & P2PKH for new wallets.
  */
 WalletService.prototype.createWallet = function(opts, cb) {
   var self = this,
@@ -263,6 +265,7 @@ WalletService.prototype.createWallet = function(opts, cb) {
         n: opts.n,
         network: opts.network,
         pubKey: pubKey.toString(),
+        singleAddress: !!opts.singleAddress,
         derivationStrategy: derivationStrategy,
         addressType: addressType,
       });
@@ -784,27 +787,40 @@ WalletService.prototype.createAddress = function(opts, cb) {
 
   opts = opts || {};
 
+  function createNewAddress(wallet, cb) {
+    self._canCreateAddress(opts.ignoreMaxGap, function(err, canCreate) {
+      if (err) return cb(err);
+      if (!canCreate) return cb(Errors.MAIN_ADDRESS_GAP_REACHED);
+
+      var address = wallet.createAddress(false);
+
+      self.storage.storeAddressAndWallet(wallet, address, function(err) {
+        if (err) return cb(err);
+
+        self._notify('NewAddress', {
+          address: address.address,
+        }, function() {
+          return cb(null, address);
+        });
+      });
+    });
+  };
+
+  function getFirstAddress(wallet, cb) {
+    self.storage.fetchAddresses(self.walletId, function(err, addresses) {
+      if (err) return cb(err);
+      if (!_.isEmpty(addresses)) return cb(null, _.first(addresses))
+      return createNewAddress(wallet, cb);
+    });
+  };
+
   self._runLocked(cb, function(cb) {
     self.getWallet({}, function(err, wallet) {
       if (err) return cb(err);
       if (!wallet.isComplete()) return cb(Errors.WALLET_NOT_COMPLETE);
 
-      self._canCreateAddress(opts.ignoreMaxGap, function(err, canCreate) {
-        if (err) return cb(err);
-        if (!canCreate) return cb(Errors.MAIN_ADDRESS_GAP_REACHED);
-
-        var address = wallet.createAddress(false);
-
-        self.storage.storeAddressAndWallet(wallet, address, function(err) {
-          if (err) return cb(err);
-
-          self._notify('NewAddress', {
-            address: address.address,
-          }, function() {
-            return cb(null, address);
-          });
-        });
-      });
+      var createFn = wallet.singleAddress ? getFirstAddress : createNewAddress;
+      return createFn(wallet, cb);
     });
   });
 };
@@ -1669,7 +1685,9 @@ WalletService.prototype._validateOutputs = function(opts, wallet, cb) {
     var output = opts.outputs[i];
     output.valid = false;
 
-    if (!checkRequired(output, ['toAddress', 'amount'], cb)) return;
+    if (!checkRequired(output, ['toAddress', 'amount'])) {
+      return new ClientError('Argument missing in output #' + (i + 1) + '.');
+    }
 
     var toAddress = {};
     try {
@@ -1744,6 +1762,8 @@ WalletService.prototype.createTxLegacy = function(opts, cb) {
       if (err) return cb(err);
       if (!wallet.isComplete()) return cb(Errors.WALLET_NOT_COMPLETE);
 
+      if (wallet.singleAddress) return cb(new ClientError('Not compatible with single-address wallets'));
+
       if (opts.payProUrl) {
         if (wallet.addressType == Constants.SCRIPT_TYPES.P2PKH && !self._clientSupportsPayProRefund()) {
           return cb(new ClientError(Errors.codes.UPGRADE_NEEDED, 'To sign this spend proposal you need to upgrade your client app.'));
@@ -1858,6 +1878,10 @@ WalletService.prototype._validateAndSanitizeTxOpts = function(wallet, opts, cb)
       }
       next();
     },
+    function(next) {
+      if (wallet.singleAddress && opts.changeAddress) return next(new ClientError('Cannot specify change address on single-address wallet'));
+      next();
+    },
     function(next) {
       if (!opts.sendMax) return next();
       if (!_.isArray(opts.outputs) || opts.outputs.length > 1) {
@@ -1899,7 +1923,7 @@ WalletService.prototype._validateAndSanitizeTxOpts = function(wallet, opts, cb)
  * @param {string} opts.outputs[].message - A message to attach to this output.
  * @param {string} opts.message - A message to attach to this transaction.
  * @param {number} opts.feePerKb - Use an alternative fee per KB for this TX.
- * @param {string} opts.changeAddress - Optional. Use this address as the change address for the tx. The address should belong to the wallet.
+ * @param {string} opts.changeAddress - Optional. Use this address as the change address for the tx. The address should belong to the wallet. In the case of singleAddress wallets, the first main address will be used.
  * @param {Boolean} opts.sendMax - Optional. Send maximum amount of funds that make sense under the specified fee/feePerKb conditions. (defaults to false).
  * @param {string} opts.payProUrl - Optional. Paypro URL for peers to verify TX
  * @param {Boolean} opts.excludeUnconfirmedUtxos[=false] - Optional. Do not use UTXOs of unconfirmed transactions as inputs
@@ -1913,6 +1937,25 @@ WalletService.prototype._validateAndSanitizeTxOpts = function(wallet, opts, cb)
 WalletService.prototype.createTx = function(opts, cb) {
   var self = this;
 
+  function getChangeAddress(wallet, cb) {
+    if (wallet.singleAddress) {
+      self.storage.fetchAddresses(self.walletId, function(err, addresses) {
+        if (err) return cb(err);
+        if (_.isEmpty(addresses)) return cb(new ClientError('The wallet has no addresses'));
+        return cb(null, _.first(addresses));
+      });
+    } else {
+      if (opts.changeAddress) {
+        self.storage.fetchAddress(opts.changeAddress, function(err, address) {
+          if (err) return cb(Errors.INVALID_CHANGE_ADDRESS);
+          return cb(null, address);
+        });
+      } else {
+        return cb(null, wallet.createAddress(true));
+      }
+    }
+  };
+
   self._runLocked(cb, function(cb) {
     var wallet, txp, changeAddress;
     async.series([
@@ -1937,16 +1980,11 @@ WalletService.prototype.createTx = function(opts, cb) {
       },
       function(next) {
         if (opts.sendMax) return next();
-        if (opts.changeAddress) {
-          self.storage.fetchAddress(opts.changeAddress, function(err, address) {
-            if (err) return next(Errors.INVALID_CHANGE_ADDRESS);
-            changeAddress = address;
-            return next();
-          });
-        } else {
-          changeAddress = wallet.createAddress(true);
-          return next();
-        }
+        getChangeAddress(wallet, function(err, address) {
+          if (err) return next(err);
+          changeAddress = address;
+          next();
+        });
       },
       function(next) {
         var txOpts = {
diff --git a/package.json b/package.json
index 6d21233..60b0e0b 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "bitcore-wallet-service",
   "description": "A service for Mutisig HD Bitcoin Wallets",
   "author": "BitPay Inc",
-  "version": "1.8.2",
+  "version": "1.9.0",
   "keywords": [
     "bitcoin",
     "copay",
diff --git a/test/integration/helpers.js b/test/integration/helpers.js
index e53d38b..f0d0cac 100644
--- a/test/integration/helpers.js
+++ b/test/integration/helpers.js
@@ -164,6 +164,7 @@ helpers.createAndJoinWallet = function(m, n, opts, cb) {
     m: m,
     n: n,
     pubKey: TestData.keyPair.pub,
+    singleAddress: !!opts.singleAddress,
   };
   if (_.isBoolean(opts.supportBIP44AndP2PKH))
     walletOpts.supportBIP44AndP2PKH = opts.supportBIP44AndP2PKH;
diff --git a/test/integration/server.js b/test/integration/server.js
index 57b5f9e..a9de253 100644
--- a/test/integration/server.js
+++ b/test/integration/server.js
@@ -2793,7 +2793,7 @@ describe('Wallet service', function() {
           });
           server.createTxLegacy(txOpts, function(err, tx) {
             should.exist(err);
-            err.message.should.contain('outputs argument missing');
+            err.message.should.contain('Argument missing in output #1.');
             done();
           });
         });
@@ -3707,7 +3707,7 @@ describe('Wallet service', function() {
             should.not.exist(err);
             should.exist(txp);
             txp.inputs.length.should.equal(3);
-            txOpts.feePerKb = 120e2;
+            txOpts.feePerKb = 160e2;
             server.createTx(txOpts, function(err, txp) {
               should.exist(err);
               should.not.exist(txp);
@@ -4209,6 +4209,95 @@ describe('Wallet service', function() {
     });
   });
 
+  describe('Single-address wallet', function() {
+    var server, wallet, firstAddress;
+    beforeEach(function(done) {
+      helpers.createAndJoinWallet(1, 2, {
+        singleAddress: true,
+      }, function(s, w) {
+        server = s;
+        wallet = w;
+        server.createAddress({}, function(err, a) {
+          should.not.exist(err);
+          should.exist(a.address);
+          firstAddress = a;
+          done();
+        });
+      });
+    });
+    it('should include singleAddress property', function(done) {
+      server.getWallet({}, function(err, wallet) {
+        should.not.exist(err);
+        wallet.singleAddress.should.be.true;
+        done();
+      });
+    });
+    it('should always return same address', function(done) {
+      firstAddress.path.should.equal('m/0/0');
+      server.createAddress({}, function(err, x) {
+        should.not.exist(err);
+        should.exist(x);
+        x.path.should.equal('m/0/0');
+        x.address.should.equal(firstAddress.address);
+        server.getMainAddresses({}, function(err, addr) {
+          should.not.exist(err);
+          addr.length.should.equal(1);
+          done();
+        });
+      });
+    });
+    it('should reuse address as change address on tx proposal creation', function(done) {
+      helpers.stubUtxos(server, wallet, 2, function() {
+        var toAddress = '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7';
+        var opts = {
+          outputs: [{
+            amount: 1e8,
+            toAddress: toAddress,
+          }],
+          feePerKb: 100e2,
+        };
+        server.createTx(opts, function(err, txp) {
+          should.not.exist(err);
+          should.exist(txp);
+          should.exist(txp.changeAddress);
+          txp.changeAddress.address.should.equal(firstAddress.address);
+          txp.changeAddress.path.should.equal(firstAddress.path);
+          done();
+        });
+      });
+    });
+    it('should not allow legacy txs', function(done) {
+      helpers.stubUtxos(server, wallet, 2, function() {
+        var toAddress = '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7';
+        var txOpts = helpers.createSimpleProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 1, TestData.copayers[0].privKey_1H_0);
+        server.createTxLegacy(txOpts, function(err, tx) {
+          should.exist(err);
+          err.message.should.contain('single-address');
+          done();
+        });
+      });
+    });
+    it('should not be able to specify custom changeAddress', function(done) {
+      helpers.stubUtxos(server, wallet, 2, function() {
+        var toAddress = '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7';
+        var opts = {
+          outputs: [{
+            amount: 1e8,
+            toAddress: toAddress,
+          }],
+          feePerKb: 100e2,
+          changeAddress: firstAddress.address,
+        };
+        server.createTx(opts, function(err, txp) {
+          should.exist(err);
+          err.message.should.contain('single-address');
+          done();
+        });
+      });
+    });
+  });
+
+
   describe('#getSendMaxInfo', function() {
     var server, wallet;
     beforeEach(function(done) {