diff --git a/src.ts/contracts/contract.ts b/src.ts/contracts/contract.ts
index 82b5e0459..39cede000 100644
--- a/src.ts/contracts/contract.ts
+++ b/src.ts/contracts/contract.ts
@@ -2,10 +2,9 @@
 
 import { Interface } from './interface';
 
-// @TODO: Move to utils?
-import { TransactionResponse } from '../providers/provider';
-import { Network } from '../providers/networks';
+import { Provider, TransactionResponse } from '../providers/provider';
 
+import { getContractAddress } from '../utils/address';
 import { ParamType } from '../utils/abi-coder';
 import { BigNumber, ConstantZero } from '../utils/bignumber';
 import { defineReadOnly, resolveProperties } from '../utils/properties';
@@ -211,6 +210,7 @@ function runMethod(contract: Contract, functionName: string, estimateOnly: boole
         throw new Error('unsupport type - ' + method.type);
     }
 }
+/*
 interface Provider {
     getNetwork(): Promise<Network>;
     getGasPrice(): Promise<BigNumber>;
@@ -219,11 +219,12 @@ interface Provider {
     estimateGas(tx: any): Promise<BigNumber>;
     sendTransaction(signedTransaction: string | Promise<string>): Promise<TransactionResponse>;
 }
-
+*/
 interface Signer {
     defaultGasLimit?: BigNumber;
     defaultGasPrice?: BigNumber;
     address?: string;
+    provider?: Provider;
 
     getAddress(): Promise<string>;
     getTransactionCount(): Promise<number>;
@@ -232,6 +233,10 @@ interface Signer {
     sign(tx: any): string | Promise<string>;
 }
 
+function isSigner(value: any): value is Signer {
+    return (value && value.provider != null);
+}
+
 export type ContractEstimate = (...params: Array<any>) => Promise<BigNumber>;
 export type ContractFunction = (...params: Array<any>) => Promise<any>;
 export type ContractEvent = (...params: Array<any>) => void;
@@ -253,11 +258,14 @@ export class Contract {
 
     readonly addressPromise: Promise<string>;
 
+    // This is only set if the contract was created with a call to deploy
+    readonly deployTransaction: TransactionResponse;
+
     // https://github.com/Microsoft/TypeScript/issues/5453
     // Once this issue is resolved (there are open PR) we can do this nicer. :)
 
-    constructor(addressOrName: string, contractInterface: Contractish, signerOrProvider: any) {
-        //if (!(this instanceof Contract)) { throw new Error('missing new'); }
+    constructor(addressOrName: string, contractInterface: Contractish, signerOrProvider: Signer | Provider) {
+        errors.checkNew(this, Contract);
 
         // @TODO: Maybe still check the addressOrName looks like a valid address or name?
         //address = getAddress(address);
@@ -269,28 +277,29 @@ export class Contract {
 
         if (!signerOrProvider) { throw new Error('missing signer or provider'); }
 
-        var signer = signerOrProvider;
-        var provider = null;
-
-        if (signerOrProvider.provider) {
-            provider = signerOrProvider.provider;
+        if (isSigner(signerOrProvider)) {
+            defineReadOnly(this, 'provider', signerOrProvider.provider);
+            defineReadOnly(this, 'signer', signerOrProvider);
         } else {
-            provider = signerOrProvider;
-            signer = null;
+            defineReadOnly(this, 'provider', signerOrProvider);
+            defineReadOnly(this, 'signer', null);
         }
 
-        defineReadOnly(this, 'signer', signer);
-        defineReadOnly(this, 'provider', provider);
-
-        if (!addressOrName) { return; }
-
-        defineReadOnly(this, 'address', addressOrName);
-        defineReadOnly(this, 'addressPromise', provider.resolveName(addressOrName));
 
         defineReadOnly(this, 'estimate', { });
         defineReadOnly(this, 'events', { });
         defineReadOnly(this, 'functions', { });
 
+        // Not connected to an on-chain instance, so do not connect functions and events
+        if (!addressOrName) {
+            defineReadOnly(this, 'address', null);
+            defineReadOnly(this, 'addressPromise', Promise.resolve(null));
+            return;
+        }
+
+        defineReadOnly(this, 'address', addressOrName || null);
+        defineReadOnly(this, 'addressPromise', this.provider.resolveName(addressOrName || null));
+
         Object.keys(this.interface.functions).forEach((name) => {
             var run = runMethod(this, name, false);
 
@@ -311,9 +320,9 @@ export class Contract {
 
             let eventCallback = null;
 
-            let addressPromise = this.addressPromise;
+            let contract = this;
             function handleEvent(log) {
-                addressPromise.then((address) => {
+                contract.addressPromise.then((address) => {
                     // Not meant for us (the topics just has the same name)
                     if (address != log.address) { return; }
 
@@ -325,12 +334,12 @@ export class Contract {
                         log.event = eventName;
                         log.parse = eventInfo.parse;
                         log.removeListener = function() {
-                            provider.removeListener(eventInfo.topics, handleEvent);
+                            contract.provider.removeListener(eventInfo.topics, handleEvent);
                         }
 
-                        log.getBlock = function() { return provider.getBlock(log.blockHash);; }
-                        log.getTransaction = function() { return provider.getTransaction(log.transactionHash); }
-                        log.getTransactionReceipt = function() { return provider.getTransactionReceipt(log.transactionHash); }
+                        log.getBlock = function() { return contract.provider.getBlock(log.blockHash);; }
+                        log.getTransaction = function() { return contract.provider.getTransaction(log.transactionHash); }
+                        log.getTransactionReceipt = function() { return contract.provider.getTransactionReceipt(log.transactionHash); }
                         log.eventSignature = eventInfo.signature;
 
                         eventCallback.apply(log, Array.prototype.slice.call(result));
@@ -349,10 +358,10 @@ export class Contract {
                     if (!value) { value = null; }
 
                     if (!value && eventCallback) {
-                        provider.removeListener(eventInfo.topics, handleEvent);
+                        contract.provider.removeListener(eventInfo.topics, handleEvent);
 
                     } else if (value && !eventCallback) {
-                        provider.on(eventInfo.topics, handleEvent);
+                        contract.provider.on(eventInfo.topics, handleEvent);
                     }
 
                     eventCallback = value;
@@ -369,11 +378,15 @@ export class Contract {
         }, this);
     }
 
-    connect(signerOrProvider) {
+    // Reconnect to a different signer or provider
+    connect(signerOrProvider: Signer | Provider): Contract {
         return new Contract(this.address, this.interface, signerOrProvider);
     }
 
-    deploy(bytecode: string, ...args): Promise<TransactionResponse> {
+    // Deploy the contract with the bytecode, resolving to the deployed address.
+    // Use contract.deployTransaction.wait() to wait until the contract has
+    // been mined.
+    deploy(bytecode: string, ...args: Array<any>): Promise<Contract> {
         if (this.signer == null) {
             throw new Error('missing signer'); // @TODO: errors.throwError
         }
@@ -381,6 +394,10 @@ export class Contract {
         // @TODO: overrides of args.length = this.interface.deployFunction.inputs.length + 1
         return this.signer.sendTransaction({
             data: this.interface.deployFunction.encode(bytecode, args)
+        }).then((tx) => {
+            let contract = new Contract(getContractAddress(tx), this.interface, this.provider);
+            defineReadOnly(contract, 'deployTransaction', tx);
+            return contract;
         });
     }
 }
diff --git a/src.ts/contracts/interface.ts b/src.ts/contracts/interface.ts
index fe5fbcdf2..a98fe815d 100644
--- a/src.ts/contracts/interface.ts
+++ b/src.ts/contracts/interface.ts
@@ -331,7 +331,7 @@ export class Interface {
     readonly deployFunction: DeployDescription;
 
     constructor(abi: Array<string | ParamType> | string) {
-        if (!(this instanceof Interface)) { throw new Error('missing new'); }
+        errors.checkNew(this, Interface);
 
         if (typeof(abi) === 'string') {
             try {
diff --git a/src.ts/providers/etherscan-provider.ts b/src.ts/providers/etherscan-provider.ts
index 9fca4e02c..68f455568 100644
--- a/src.ts/providers/etherscan-provider.ts
+++ b/src.ts/providers/etherscan-provider.ts
@@ -5,6 +5,7 @@ import { Network } from './networks';
 import { hexlify, hexStripZeros } from '../utils/convert';
 import { fetchJson } from '../utils/web';
 
+import * as errors from '../utils/errors';
 
 // The transaction has already been sanitized by the calls in Provider
 function getTransactionString(transaction: TransactionRequest): string {
@@ -70,6 +71,7 @@ export class EtherscanProvider extends Provider{
     constructor(network?: Network | string, apiKey?: string) {
 
         super(network || 'homestead');
+        errors.checkNew(this, EtherscanProvider);
 
         let name = 'invalid';
         if (this.network) { name = this.network.name; }
diff --git a/src.ts/providers/fallback-provider.ts b/src.ts/providers/fallback-provider.ts
index 90078a002..746bd2dd7 100644
--- a/src.ts/providers/fallback-provider.ts
+++ b/src.ts/providers/fallback-provider.ts
@@ -46,15 +46,16 @@ export class FallbackProvider extends Provider {
     private _providers: Array<Provider>;
 
     constructor(providers: Array<Provider>) {
-        //if (!(this instanceof FallbackProvider)) { throw new Error('missing new'); }
 
         if (providers.length === 0) { throw new Error('no providers'); }
 
         let ready = checkNetworks(providers.map((p) => p.network));
         if (ready) {
             super(providers[0].network);
+            errors.checkNew(this, FallbackProvider);
         } else {
             super(null);
+            errors.checkNew(this, FallbackProvider);
 
             // We re-assign the ready function to make sure all networks actually match
             this.ready = Promise.all(providers.map((p) => p.getNetwork())).then((networks) => {
@@ -65,6 +66,7 @@ export class FallbackProvider extends Provider {
             });
         }
 
+
         this._providers = providers.slice(0);
     }
 
diff --git a/src.ts/providers/infura-provider.ts b/src.ts/providers/infura-provider.ts
index 17534906b..b66180e91 100644
--- a/src.ts/providers/infura-provider.ts
+++ b/src.ts/providers/infura-provider.ts
@@ -9,7 +9,6 @@ export class InfuraProvider extends JsonRpcProvider {
     readonly apiAccessToken: string;
 
     constructor(network?: Network | string, apiAccessToken?: string) {
-        //errors.checkNew(this, InfuraProvider);
 
         network = getNetwork(network || 'homestead');
 
@@ -32,6 +31,8 @@ export class InfuraProvider extends JsonRpcProvider {
         }
 
         super('https://' + host + '/' + (apiAccessToken || ''), network);
+        errors.checkNew(this, InfuraProvider);
+
         this.apiAccessToken = (apiAccessToken || null);
     }
 
diff --git a/src.ts/providers/ipc-provider.ts b/src.ts/providers/ipc-provider.ts
index 7390d6c18..939ee60e0 100644
--- a/src.ts/providers/ipc-provider.ts
+++ b/src.ts/providers/ipc-provider.ts
@@ -9,13 +9,13 @@ import * as errors from '../utils/errors';
 export class IpcProvider extends JsonRpcProvider {
     readonly path: string;
     constructor(path: string, network?: Network | string) {
-        //errors.checkNew(this, IpcProvider);
-
         if (path == null) {
             errors.throwError('missing path', errors.MISSING_ARGUMENT, { arg: 'path' });
         }
 
         super('ipc://' + path, network);
+        errors.checkNew(this, IpcProvider);
+
         this.path = path;
     }
 
diff --git a/src.ts/providers/json-rpc-provider.ts b/src.ts/providers/json-rpc-provider.ts
index 2bbbcd18a..8d0d1ad16 100644
--- a/src.ts/providers/json-rpc-provider.ts
+++ b/src.ts/providers/json-rpc-provider.ts
@@ -67,7 +67,7 @@ export class JsonRpcSigner {
 //    private _syncAddress: boolean;
 
     constructor(provider: JsonRpcProvider, address?: string) {
-        //errors.checkNew(this, JsonRpcSigner);
+        errors.checkNew(this, JsonRpcSigner);
 
         this.provider = provider;
 
@@ -161,7 +161,6 @@ export class JsonRpcProvider extends Provider {
     private _pendingFilter: Promise<number>;
 
     constructor(url?: ConnectionInfo | string, network?: Network | string) {
-        //errors.checkNew(this, JsonRpcProvider);
 
         // One parameter, but it is a network name, so swap it with the URL
         if (typeof(url) === 'string') {
@@ -172,6 +171,7 @@ export class JsonRpcProvider extends Provider {
         }
 
         super(network);
+        errors.checkNew(this, JsonRpcProvider);
 
         // Default URL
         if (!url) { url = 'http://localhost:8545'; }
diff --git a/src.ts/providers/provider.ts b/src.ts/providers/provider.ts
index d8dd6e29f..c326716b7 100644
--- a/src.ts/providers/provider.ts
+++ b/src.ts/providers/provider.ts
@@ -2,11 +2,8 @@
 
 //import inherits = require('inherits');
 
-//import networks = require('./networks.json');
-
-import { getAddress } from '../utils/address';
+import { getAddress, getContractAddress } from '../utils/address';
 import { BigNumber, bigNumberify, BigNumberish } from '../utils/bignumber';
-import { getContractAddress } from '../utils/contract-address';
 import { Arrayish, hexlify, hexStripZeros, isHexString, stripZeros } from '../utils/convert';
 import { toUtf8String } from '../utils/utf8';
 import { decode as rlpDecode, encode as rlpEncode } from '../utils/rlp';
@@ -604,7 +601,7 @@ export class Provider {
      */
 
     constructor(network: string | Network) {
-        //if (!(this instanceof Provider)) { throw new Error('missing new'); }
+        errors.checkNew(this, Provider);
 
         network = getNetwork(network);
 
@@ -803,7 +800,7 @@ export class Provider {
     }
 
 
-    getBalance(addressOrName: string | Promise<string>, blockTag: BlockTag | Promise<BlockTag>): Promise<BigNumber> {
+    getBalance(addressOrName: string | Promise<string>, blockTag?: BlockTag | Promise<BlockTag>): Promise<BigNumber> {
         return this.ready.then(() => {
             return resolveProperties({ addressOrName: addressOrName, blockTag: blockTag }).then(({ addressOrName, blockTag }) => {
                 return this.resolveName(addressOrName).then((address) => {
@@ -816,7 +813,7 @@ export class Provider {
         });
     }
 
-    getTransactionCount(addressOrName: string | Promise<string>, blockTag: BlockTag | Promise<BlockTag>): Promise<number> {
+    getTransactionCount(addressOrName: string | Promise<string>, blockTag?: BlockTag | Promise<BlockTag>): Promise<number> {
         return this.ready.then(() => {
             return resolveProperties({ addressOrName: addressOrName, blockTag: blockTag }).then(({ addressOrName, blockTag }) => {
                 return this.resolveName(addressOrName).then((address) => {
@@ -831,7 +828,7 @@ export class Provider {
         });
     }
 
-    getCode(addressOrName: string | Promise<string>, blockTag: BlockTag | Promise<BlockTag>): Promise<string> {
+    getCode(addressOrName: string | Promise<string>, blockTag?: BlockTag | Promise<BlockTag>): Promise<string> {
         return this.ready.then(() => {
             return resolveProperties({ addressOrName: addressOrName, blockTag: blockTag }).then(({ addressOrName, blockTag }) => {
                 return this.resolveName(addressOrName).then((address) => {
@@ -844,7 +841,7 @@ export class Provider {
         });
     }
 
-    getStorageAt(addressOrName: string | Promise<string>, position: BigNumberish | Promise<BigNumberish>, blockTag: BlockTag | Promise<BlockTag>): Promise<string> {
+    getStorageAt(addressOrName: string | Promise<string>, position: BigNumberish | Promise<BigNumberish>, blockTag?: BlockTag | Promise<BlockTag>): Promise<string> {
         return this.ready.then(() => {
             return resolveProperties({ addressOrName: addressOrName, position: position, blockTag: blockTag }).then(({ addressOrName, position, blockTag }) => {
                 return this.resolveName(addressOrName).then((address) => {
diff --git a/src.ts/providers/web3-provider.ts b/src.ts/providers/web3-provider.ts
index 9f74169c1..42c108fb2 100644
--- a/src.ts/providers/web3-provider.ts
+++ b/src.ts/providers/web3-provider.ts
@@ -24,7 +24,6 @@ export class Web3Provider extends JsonRpcProvider {
     readonly _web3Provider: AsyncProvider;
 
     constructor(web3Provider: AsyncProvider, network?: Network | string) {
-        //errors.checkNew(this, Web3Provider);
 
         if (!web3Provider || !web3Provider.sendAsync) {
             errors.throwError(
@@ -38,6 +37,8 @@ export class Web3Provider extends JsonRpcProvider {
         var url = web3Provider.host || web3Provider.path || 'unknown';
 
         super(url, network);
+        errors.checkNew(this, Web3Provider);
+
         this._web3Provider = web3Provider;
     }
 
diff --git a/src.ts/utils/address.ts b/src.ts/utils/address.ts
index a8737df45..b3681ae4e 100644
--- a/src.ts/utils/address.ts
+++ b/src.ts/utils/address.ts
@@ -1,12 +1,16 @@
 'use strict';
 
+// We use this for base 36 maths
 import BN = require('bn.js');
 
-import { arrayify } from './convert';
+import { BigNumber } from './bignumber';
+import { arrayify, Arrayish, stripZeros, hexlify } from './convert';
 import { keccak256 } from './keccak256';
+import { encode } from './rlp';
 
 import errors = require('./errors');
 
+
 function getChecksumAddress(address: string): string {
     if (typeof(address) !== 'string' || !address.match(/^0x[0-9A-Fa-f]{40}$/)) {
         errors.throwError('invalid address', errors.INVALID_ARGUMENT, { arg: 'address', value: address });
@@ -118,3 +122,14 @@ export function getAddress(address: string, icapFormat?: boolean): string {
     return result;
 }
 
+// http://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
+export function getContractAddress(transaction: { from: string, nonce: Arrayish | BigNumber | number }) {
+    if (!transaction.from) { throw new Error('missing from address'); }
+    var nonce = transaction.nonce;
+
+    return getAddress('0x' + keccak256(encode([
+        getAddress(transaction.from),
+        stripZeros(hexlify(nonce))
+    ])).substring(26));
+}
+
diff --git a/src.ts/utils/contract-address.ts b/src.ts/utils/contract-address.ts
deleted file mode 100644
index 8f2b3474c..000000000
--- a/src.ts/utils/contract-address.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-'use strict';
-
-import { getAddress } from './address';
-import { BigNumber } from './bignumber';
-import { Arrayish, stripZeros, hexlify } from './convert';
-import { keccak256 } from './keccak256';
-import { encode } from './rlp';
-
-// http://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
-export function getContractAddress(transaction: { from: string, nonce: Arrayish | BigNumber | number }) {
-    if (!transaction.from) { throw new Error('missing from address'); }
-    var nonce = transaction.nonce;
-
-    return getAddress('0x' + keccak256(encode([
-        getAddress(transaction.from),
-        stripZeros(hexlify(nonce))
-    ])).substring(26));
-}
diff --git a/src.ts/utils/index.ts b/src.ts/utils/index.ts
index 622d9e06e..e443f748e 100644
--- a/src.ts/utils/index.ts
+++ b/src.ts/utils/index.ts
@@ -3,11 +3,10 @@
 // This is SUPER useful, but adds 140kb (even zipped, adds 40kb)
 //var unorm = require('unorm');
 
-import { getAddress } from './address';
+import { getAddress, getContractAddress } from './address';
 import { AbiCoder, defaultAbiCoder, parseSignature } from './abi-coder';
 import * as base64 from './base64';
 import * as bigNumber from './bignumber';
-import { getContractAddress } from './contract-address';
 import * as convert from './convert';
 import { id } from './id';
 import { keccak256 } from './keccak256';
diff --git a/src.ts/wallet/hdnode.ts b/src.ts/wallet/hdnode.ts
index 5fdd8dfa0..84594457c 100644
--- a/src.ts/wallet/hdnode.ts
+++ b/src.ts/wallet/hdnode.ts
@@ -15,6 +15,8 @@ import { pbkdf2 } from '../utils/pbkdf2';
 import { createSha512Hmac } from '../utils/hmac';
 import { sha256 } from '../utils/sha2';
 
+import * as errors from '../utils/errors';
+
 // "Bitcoin seed"
 var MasterSecret = toUtf8Bytes('Bitcoin seed');
 
@@ -46,7 +48,7 @@ export class HDNode {
 
     // @TODO: Private constructor?
     constructor(keyPair: secp256k1.KeyPair, chainCode: Uint8Array, index: number, depth: number, mnemonic: string, path: string) {
-        //if (!(this instanceof HDNode)) { throw new Error('missing new'); }
+        errors.checkNew(this, HDNode);
 
         this.keyPair = keyPair;
 
diff --git a/src.ts/wallet/signing-key.ts b/src.ts/wallet/signing-key.ts
index 2e83bb024..2b067fe21 100644
--- a/src.ts/wallet/signing-key.ts
+++ b/src.ts/wallet/signing-key.ts
@@ -27,7 +27,7 @@ export class SigningKey {
     private readonly keyPair: secp256k1.KeyPair;
 
     constructor(privateKey: any) {
-        //errors.checkNew(this, SigningKey);
+        errors.checkNew(this, SigningKey);
 
         if (privateKey.privateKey) {
             this.mnemonic = privateKey.mnemonic;
diff --git a/src/contracts/contract.d.ts b/src/contracts/contract.d.ts
index ed871174c..12fe670f9 100644
--- a/src/contracts/contract.d.ts
+++ b/src/contracts/contract.d.ts
@@ -1,20 +1,12 @@
 import { Interface } from './interface';
-import { TransactionResponse } from '../providers/provider';
-import { Network } from '../providers/networks';
+import { Provider, TransactionResponse } from '../providers/provider';
 import { ParamType } from '../utils/abi-coder';
 import { BigNumber } from '../utils/bignumber';
-interface Provider {
-    getNetwork(): Promise<Network>;
-    getGasPrice(): Promise<BigNumber>;
-    getTransactionCount(address: string | Promise<string>): Promise<number>;
-    call(data: string): Promise<string>;
-    estimateGas(tx: any): Promise<BigNumber>;
-    sendTransaction(signedTransaction: string | Promise<string>): Promise<TransactionResponse>;
-}
 interface Signer {
     defaultGasLimit?: BigNumber;
     defaultGasPrice?: BigNumber;
     address?: string;
+    provider?: Provider;
     getAddress(): Promise<string>;
     getTransactionCount(): Promise<number>;
     estimateGas(tx: any): Promise<BigNumber>;
@@ -37,8 +29,9 @@ export declare class Contract {
     readonly functions: Bucket<ContractFunction>;
     readonly events: Bucket<ContractEvent>;
     readonly addressPromise: Promise<string>;
-    constructor(addressOrName: string, contractInterface: Contractish, signerOrProvider: any);
-    connect(signerOrProvider: any): Contract;
-    deploy(bytecode: string, ...args: any[]): Promise<TransactionResponse>;
+    readonly deployTransaction: TransactionResponse;
+    constructor(addressOrName: string, contractInterface: Contractish, signerOrProvider: Signer | Provider);
+    connect(signerOrProvider: Signer | Provider): Contract;
+    deploy(bytecode: string, ...args: Array<any>): Promise<Contract>;
 }
 export {};
diff --git a/src/contracts/contract.js b/src/contracts/contract.js
index 40957de02..a6f3e8614 100644
--- a/src/contracts/contract.js
+++ b/src/contracts/contract.js
@@ -8,6 +8,7 @@ var __importStar = (this && this.__importStar) || function (mod) {
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 var interface_1 = require("./interface");
+var address_1 = require("../utils/address");
 var bignumber_1 = require("../utils/bignumber");
 var properties_1 = require("../utils/properties");
 var errors = __importStar(require("../utils/errors"));
@@ -193,12 +194,15 @@ function runMethod(contract, functionName, estimateOnly) {
         throw new Error('unsupport type - ' + method.type);
     };
 }
+function isSigner(value) {
+    return (value && value.provider != null);
+}
 var Contract = /** @class */ (function () {
     // https://github.com/Microsoft/TypeScript/issues/5453
     // Once this issue is resolved (there are open PR) we can do this nicer. :)
     function Contract(addressOrName, contractInterface, signerOrProvider) {
-        //if (!(this instanceof Contract)) { throw new Error('missing new'); }
         var _this = this;
+        errors.checkNew(this, Contract);
         // @TODO: Maybe still check the addressOrName looks like a valid address or name?
         //address = getAddress(address);
         if (contractInterface instanceof interface_1.Interface) {
@@ -210,25 +214,25 @@ var Contract = /** @class */ (function () {
         if (!signerOrProvider) {
             throw new Error('missing signer or provider');
         }
-        var signer = signerOrProvider;
-        var provider = null;
-        if (signerOrProvider.provider) {
-            provider = signerOrProvider.provider;
+        if (isSigner(signerOrProvider)) {
+            properties_1.defineReadOnly(this, 'provider', signerOrProvider.provider);
+            properties_1.defineReadOnly(this, 'signer', signerOrProvider);
         }
         else {
-            provider = signerOrProvider;
-            signer = null;
+            properties_1.defineReadOnly(this, 'provider', signerOrProvider);
+            properties_1.defineReadOnly(this, 'signer', null);
         }
-        properties_1.defineReadOnly(this, 'signer', signer);
-        properties_1.defineReadOnly(this, 'provider', provider);
-        if (!addressOrName) {
-            return;
-        }
-        properties_1.defineReadOnly(this, 'address', addressOrName);
-        properties_1.defineReadOnly(this, 'addressPromise', provider.resolveName(addressOrName));
         properties_1.defineReadOnly(this, 'estimate', {});
         properties_1.defineReadOnly(this, 'events', {});
         properties_1.defineReadOnly(this, 'functions', {});
+        // Not connected to an on-chain instance, so do not connect functions and events
+        if (!addressOrName) {
+            properties_1.defineReadOnly(this, 'address', null);
+            properties_1.defineReadOnly(this, 'addressPromise', Promise.resolve(null));
+            return;
+        }
+        properties_1.defineReadOnly(this, 'address', addressOrName || null);
+        properties_1.defineReadOnly(this, 'addressPromise', this.provider.resolveName(addressOrName || null));
         Object.keys(this.interface.functions).forEach(function (name) {
             var run = runMethod(_this, name, false);
             if (_this[name] == null) {
@@ -245,9 +249,9 @@ var Contract = /** @class */ (function () {
         Object.keys(this.interface.events).forEach(function (eventName) {
             var eventInfo = _this.interface.events[eventName];
             var eventCallback = null;
-            var addressPromise = _this.addressPromise;
+            var contract = _this;
             function handleEvent(log) {
-                addressPromise.then(function (address) {
+                contract.addressPromise.then(function (address) {
                     // Not meant for us (the topics just has the same name)
                     if (address != log.address) {
                         return;
@@ -259,11 +263,11 @@ var Contract = /** @class */ (function () {
                         log.event = eventName;
                         log.parse = eventInfo.parse;
                         log.removeListener = function () {
-                            provider.removeListener(eventInfo.topics, handleEvent);
+                            contract.provider.removeListener(eventInfo.topics, handleEvent);
                         };
-                        log.getBlock = function () { return provider.getBlock(log.blockHash); ; };
-                        log.getTransaction = function () { return provider.getTransaction(log.transactionHash); };
-                        log.getTransactionReceipt = function () { return provider.getTransactionReceipt(log.transactionHash); };
+                        log.getBlock = function () { return contract.provider.getBlock(log.blockHash); ; };
+                        log.getTransaction = function () { return contract.provider.getTransaction(log.transactionHash); };
+                        log.getTransactionReceipt = function () { return contract.provider.getTransactionReceipt(log.transactionHash); };
                         log.eventSignature = eventInfo.signature;
                         eventCallback.apply(log, Array.prototype.slice.call(result));
                     }
@@ -282,10 +286,10 @@ var Contract = /** @class */ (function () {
                         value = null;
                     }
                     if (!value && eventCallback) {
-                        provider.removeListener(eventInfo.topics, handleEvent);
+                        contract.provider.removeListener(eventInfo.topics, handleEvent);
                     }
                     else if (value && !eventCallback) {
-                        provider.on(eventInfo.topics, handleEvent);
+                        contract.provider.on(eventInfo.topics, handleEvent);
                     }
                     eventCallback = value;
                 }
@@ -297,10 +301,15 @@ var Contract = /** @class */ (function () {
             Object.defineProperty(_this.events, eventName, property);
         }, this);
     }
+    // Reconnect to a different signer or provider
     Contract.prototype.connect = function (signerOrProvider) {
         return new Contract(this.address, this.interface, signerOrProvider);
     };
+    // Deploy the contract with the bytecode, resolving to the deployed address.
+    // Use contract.deployTransaction.wait() to wait until the contract has
+    // been mined.
     Contract.prototype.deploy = function (bytecode) {
+        var _this = this;
         var args = [];
         for (var _i = 1; _i < arguments.length; _i++) {
             args[_i - 1] = arguments[_i];
@@ -311,6 +320,10 @@ var Contract = /** @class */ (function () {
         // @TODO: overrides of args.length = this.interface.deployFunction.inputs.length + 1
         return this.signer.sendTransaction({
             data: this.interface.deployFunction.encode(bytecode, args)
+        }).then(function (tx) {
+            var contract = new Contract(address_1.getContractAddress(tx), _this.interface, _this.provider);
+            properties_1.defineReadOnly(contract, 'deployTransaction', tx);
+            return contract;
         });
     };
     return Contract;
diff --git a/src/contracts/interface.js b/src/contracts/interface.js
index 00a7fab93..421d05fa2 100644
--- a/src/contracts/interface.js
+++ b/src/contracts/interface.js
@@ -303,9 +303,7 @@ function addMethod(method) {
 var Interface = /** @class */ (function () {
     function Interface(abi) {
         var _this = this;
-        if (!(this instanceof Interface)) {
-            throw new Error('missing new');
-        }
+        errors.checkNew(this, Interface);
         if (typeof (abi) === 'string') {
             try {
                 abi = JSON.parse(abi);
diff --git a/src/providers/etherscan-provider.js b/src/providers/etherscan-provider.js
index 30d1b2514..8c717d374 100644
--- a/src/providers/etherscan-provider.js
+++ b/src/providers/etherscan-provider.js
@@ -9,10 +9,18 @@ var __extends = (this && this.__extends) || (function () {
         d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
     };
 })();
+var __importStar = (this && this.__importStar) || function (mod) {
+    if (mod && mod.__esModule) return mod;
+    var result = {};
+    if (mod != null) for (var k in mod) if (Object.hasOwnProperty.call(mod, k)) result[k] = mod[k];
+    result["default"] = mod;
+    return result;
+};
 Object.defineProperty(exports, "__esModule", { value: true });
 var provider_1 = require("./provider");
 var convert_1 = require("../utils/convert");
 var web_1 = require("../utils/web");
+var errors = __importStar(require("../utils/errors"));
 // The transaction has already been sanitized by the calls in Provider
 function getTransactionString(transaction) {
     var result = [];
@@ -75,6 +83,7 @@ var EtherscanProvider = /** @class */ (function (_super) {
     __extends(EtherscanProvider, _super);
     function EtherscanProvider(network, apiKey) {
         var _this = _super.call(this, network || 'homestead') || this;
+        errors.checkNew(_this, EtherscanProvider);
         var name = 'invalid';
         if (_this.network) {
             name = _this.network.name;
diff --git a/src/providers/fallback-provider.js b/src/providers/fallback-provider.js
index 4966d47da..3020f2908 100644
--- a/src/providers/fallback-provider.js
+++ b/src/providers/fallback-provider.js
@@ -50,7 +50,6 @@ function checkNetworks(networks) {
 var FallbackProvider = /** @class */ (function (_super) {
     __extends(FallbackProvider, _super);
     function FallbackProvider(providers) {
-        //if (!(this instanceof FallbackProvider)) { throw new Error('missing new'); }
         var _this = this;
         if (providers.length === 0) {
             throw new Error('no providers');
@@ -58,9 +57,11 @@ var FallbackProvider = /** @class */ (function (_super) {
         var ready = checkNetworks(providers.map(function (p) { return p.network; }));
         if (ready) {
             _this = _super.call(this, providers[0].network) || this;
+            errors.checkNew(_this, FallbackProvider);
         }
         else {
             _this = _super.call(this, null) || this;
+            errors.checkNew(_this, FallbackProvider);
             // We re-assign the ready function to make sure all networks actually match
             _this.ready = Promise.all(providers.map(function (p) { return p.getNetwork(); })).then(function (networks) {
                 if (!checkNetworks(networks)) {
diff --git a/src/providers/infura-provider.js b/src/providers/infura-provider.js
index f7a1bd97d..64011b2c6 100644
--- a/src/providers/infura-provider.js
+++ b/src/providers/infura-provider.js
@@ -23,7 +23,6 @@ var errors = __importStar(require("../utils/errors"));
 var InfuraProvider = /** @class */ (function (_super) {
     __extends(InfuraProvider, _super);
     function InfuraProvider(network, apiAccessToken) {
-        //errors.checkNew(this, InfuraProvider);
         var _this = this;
         network = networks_1.getNetwork(network || 'homestead');
         var host = null;
@@ -44,6 +43,7 @@ var InfuraProvider = /** @class */ (function (_super) {
                 throw new Error('unsupported network');
         }
         _this = _super.call(this, 'https://' + host + '/' + (apiAccessToken || ''), network) || this;
+        errors.checkNew(_this, InfuraProvider);
         _this.apiAccessToken = (apiAccessToken || null);
         return _this;
     }
diff --git a/src/providers/ipc-provider.js b/src/providers/ipc-provider.js
index 91db4ee46..3d2b7309c 100644
--- a/src/providers/ipc-provider.js
+++ b/src/providers/ipc-provider.js
@@ -26,12 +26,12 @@ var errors = __importStar(require("../utils/errors"));
 var IpcProvider = /** @class */ (function (_super) {
     __extends(IpcProvider, _super);
     function IpcProvider(path, network) {
-        //errors.checkNew(this, IpcProvider);
         var _this = this;
         if (path == null) {
             errors.throwError('missing path', errors.MISSING_ARGUMENT, { arg: 'path' });
         }
         _this = _super.call(this, 'ipc://' + path, network) || this;
+        errors.checkNew(_this, IpcProvider);
         _this.path = path;
         return _this;
     }
diff --git a/src/providers/json-rpc-provider.js b/src/providers/json-rpc-provider.js
index 08ea8075e..3125080c3 100644
--- a/src/providers/json-rpc-provider.js
+++ b/src/providers/json-rpc-provider.js
@@ -77,7 +77,7 @@ function getLowerCase(value) {
 var JsonRpcSigner = /** @class */ (function () {
     //    private _syncAddress: boolean;
     function JsonRpcSigner(provider, address) {
-        //errors.checkNew(this, JsonRpcSigner);
+        errors.checkNew(this, JsonRpcSigner);
         this.provider = provider;
         // Statically attach to a given address
         if (address) {
@@ -165,7 +165,6 @@ exports.JsonRpcSigner = JsonRpcSigner;
 var JsonRpcProvider = /** @class */ (function (_super) {
     __extends(JsonRpcProvider, _super);
     function JsonRpcProvider(url, network) {
-        //errors.checkNew(this, JsonRpcProvider);
         var _this = this;
         // One parameter, but it is a network name, so swap it with the URL
         if (typeof (url) === 'string') {
@@ -175,6 +174,7 @@ var JsonRpcProvider = /** @class */ (function (_super) {
             }
         }
         _this = _super.call(this, network) || this;
+        errors.checkNew(_this, JsonRpcProvider);
         // Default URL
         if (!url) {
             url = 'http://localhost:8545';
diff --git a/src/providers/provider.d.ts b/src/providers/provider.d.ts
index a032d7390..67cdb75c1 100644
--- a/src/providers/provider.d.ts
+++ b/src/providers/provider.d.ts
@@ -98,10 +98,10 @@ export declare class Provider {
     waitForTransaction(transactionHash: string, timeout?: number): Promise<TransactionResponse>;
     getBlockNumber(): Promise<number>;
     getGasPrice(): Promise<BigNumber>;
-    getBalance(addressOrName: string | Promise<string>, blockTag: BlockTag | Promise<BlockTag>): Promise<BigNumber>;
-    getTransactionCount(addressOrName: string | Promise<string>, blockTag: BlockTag | Promise<BlockTag>): Promise<number>;
-    getCode(addressOrName: string | Promise<string>, blockTag: BlockTag | Promise<BlockTag>): Promise<string>;
-    getStorageAt(addressOrName: string | Promise<string>, position: BigNumberish | Promise<BigNumberish>, blockTag: BlockTag | Promise<BlockTag>): Promise<string>;
+    getBalance(addressOrName: string | Promise<string>, blockTag?: BlockTag | Promise<BlockTag>): Promise<BigNumber>;
+    getTransactionCount(addressOrName: string | Promise<string>, blockTag?: BlockTag | Promise<BlockTag>): Promise<number>;
+    getCode(addressOrName: string | Promise<string>, blockTag?: BlockTag | Promise<BlockTag>): Promise<string>;
+    getStorageAt(addressOrName: string | Promise<string>, position: BigNumberish | Promise<BigNumberish>, blockTag?: BlockTag | Promise<BlockTag>): Promise<string>;
     sendTransaction(signedTransaction: string | Promise<string>): Promise<string>;
     call(transaction: TransactionRequest): Promise<string>;
     estimateGas(transaction: TransactionRequest): Promise<BigNumber>;
diff --git a/src/providers/provider.js b/src/providers/provider.js
index 19826bdfe..2f8aa1239 100644
--- a/src/providers/provider.js
+++ b/src/providers/provider.js
@@ -8,10 +8,8 @@ var __importStar = (this && this.__importStar) || function (mod) {
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 //import inherits = require('inherits');
-//import networks = require('./networks.json');
 var address_1 = require("../utils/address");
 var bignumber_1 = require("../utils/bignumber");
-var contract_address_1 = require("../utils/contract-address");
 var convert_1 = require("../utils/convert");
 var utf8_1 = require("../utils/utf8");
 var rlp_1 = require("../utils/rlp");
@@ -194,7 +192,7 @@ function checkTransactionResponse(transaction) {
     }
     // If to and creates are empty, populate the creates from the transaction
     if (transaction.to == null && transaction.creates == null) {
-        transaction.creates = contract_address_1.getContractAddress(transaction);
+        transaction.creates = address_1.getContractAddress(transaction);
     }
     if (!transaction.raw) {
         // Very loose providers (e.g. TestRPC) don't provide a signature or raw
@@ -438,7 +436,7 @@ var Provider = /** @class */ (function () {
      *    - Otherwise, the sub-class must assign a Promise to ready
      */
     function Provider(network) {
-        //if (!(this instanceof Provider)) { throw new Error('missing new'); }
+        errors.checkNew(this, Provider);
         network = networks_1.getNetwork(network);
         if (network) {
             this._network = network;
diff --git a/src/providers/web3-provider.js b/src/providers/web3-provider.js
index 6b9bed2a5..d80e7bec1 100644
--- a/src/providers/web3-provider.js
+++ b/src/providers/web3-provider.js
@@ -22,7 +22,6 @@ var errors = __importStar(require("../utils/errors"));
 var Web3Provider = /** @class */ (function (_super) {
     __extends(Web3Provider, _super);
     function Web3Provider(web3Provider, network) {
-        //errors.checkNew(this, Web3Provider);
         var _this = this;
         if (!web3Provider || !web3Provider.sendAsync) {
             errors.throwError('invalid web3Provider', errors.INVALID_ARGUMENT, { arg: 'web3Provider', value: web3Provider });
@@ -30,6 +29,7 @@ var Web3Provider = /** @class */ (function (_super) {
         // HTTP has a host; IPC has a path.
         var url = web3Provider.host || web3Provider.path || 'unknown';
         _this = _super.call(this, url, network) || this;
+        errors.checkNew(_this, Web3Provider);
         _this._web3Provider = web3Provider;
         return _this;
     }
diff --git a/src/utils/address.d.ts b/src/utils/address.d.ts
index 55cb0ea8f..8ac6ebd84 100644
--- a/src/utils/address.d.ts
+++ b/src/utils/address.d.ts
@@ -1 +1,7 @@
+import { BigNumber } from './bignumber';
+import { Arrayish } from './convert';
 export declare function getAddress(address: string, icapFormat?: boolean): string;
+export declare function getContractAddress(transaction: {
+    from: string;
+    nonce: Arrayish | BigNumber | number;
+}): string;
diff --git a/src/utils/address.js b/src/utils/address.js
index 270ae5556..4aebad762 100644
--- a/src/utils/address.js
+++ b/src/utils/address.js
@@ -1,8 +1,10 @@
 'use strict';
 Object.defineProperty(exports, "__esModule", { value: true });
+// We use this for base 36 maths
 var BN = require("bn.js");
 var convert_1 = require("./convert");
 var keccak256_1 = require("./keccak256");
+var rlp_1 = require("./rlp");
 var errors = require("./errors");
 function getChecksumAddress(address) {
     if (typeof (address) !== 'string' || !address.match(/^0x[0-9A-Fa-f]{40}$/)) {
@@ -104,3 +106,15 @@ function getAddress(address, icapFormat) {
     return result;
 }
 exports.getAddress = getAddress;
+// http://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
+function getContractAddress(transaction) {
+    if (!transaction.from) {
+        throw new Error('missing from address');
+    }
+    var nonce = transaction.nonce;
+    return getAddress('0x' + keccak256_1.keccak256(rlp_1.encode([
+        getAddress(transaction.from),
+        convert_1.stripZeros(convert_1.hexlify(nonce))
+    ])).substring(26));
+}
+exports.getContractAddress = getContractAddress;
diff --git a/src/utils/index.d.ts b/src/utils/index.d.ts
index e6485fb0c..a8cc86d7e 100644
--- a/src/utils/index.d.ts
+++ b/src/utils/index.d.ts
@@ -1,8 +1,7 @@
-import { getAddress } from './address';
+import { getAddress, getContractAddress } from './address';
 import { AbiCoder, parseSignature } from './abi-coder';
 import * as base64 from './base64';
 import * as bigNumber from './bignumber';
-import { getContractAddress } from './contract-address';
 import * as convert from './convert';
 import { id } from './id';
 import { keccak256 } from './keccak256';
diff --git a/src/utils/index.js b/src/utils/index.js
index 6978009b2..5a463c4c9 100644
--- a/src/utils/index.js
+++ b/src/utils/index.js
@@ -13,7 +13,6 @@ var address_1 = require("./address");
 var abi_coder_1 = require("./abi-coder");
 var base64 = __importStar(require("./base64"));
 var bigNumber = __importStar(require("./bignumber"));
-var contract_address_1 = require("./contract-address");
 var convert = __importStar(require("./convert"));
 var id_1 = require("./id");
 var keccak256_1 = require("./keccak256");
@@ -50,7 +49,7 @@ exports.default = {
     namehash: namehash_1.namehash,
     id: id_1.id,
     getAddress: address_1.getAddress,
-    getContractAddress: contract_address_1.getContractAddress,
+    getContractAddress: address_1.getContractAddress,
     formatEther: units.formatEther,
     parseEther: units.parseEther,
     formatUnits: units.formatUnits,
diff --git a/src/wallet/hdnode.js b/src/wallet/hdnode.js
index c1b96cf7d..6e65284bb 100644
--- a/src/wallet/hdnode.js
+++ b/src/wallet/hdnode.js
@@ -21,6 +21,7 @@ var utf8_1 = require("../utils/utf8");
 var pbkdf2_1 = require("../utils/pbkdf2");
 var hmac_1 = require("../utils/hmac");
 var sha2_1 = require("../utils/sha2");
+var errors = __importStar(require("../utils/errors"));
 // "Bitcoin seed"
 var MasterSecret = utf8_1.toUtf8Bytes('Bitcoin seed');
 var HardenedBit = 0x80000000;
@@ -35,7 +36,7 @@ function getLowerMask(bits) {
 var HDNode = /** @class */ (function () {
     // @TODO: Private constructor?
     function HDNode(keyPair, chainCode, index, depth, mnemonic, path) {
-        //if (!(this instanceof HDNode)) { throw new Error('missing new'); }
+        errors.checkNew(this, HDNode);
         this.keyPair = keyPair;
         this.privateKey = convert_1.hexlify(keyPair.priv.toArray('be', 32));
         this.publicKey = '0x' + keyPair.getPublic(true, 'hex');
diff --git a/src/wallet/signing-key.js b/src/wallet/signing-key.js
index 0ba18b592..86fc84ad2 100644
--- a/src/wallet/signing-key.js
+++ b/src/wallet/signing-key.js
@@ -19,7 +19,7 @@ var keccak256_1 = require("../utils/keccak256");
 var errors = require("../utils/errors");
 var SigningKey = /** @class */ (function () {
     function SigningKey(privateKey) {
-        //errors.checkNew(this, SigningKey);
+        errors.checkNew(this, SigningKey);
         if (privateKey.privateKey) {
             this.mnemonic = privateKey.mnemonic;
             this.path = privateKey.path;