diff --git a/README.md b/README.md
index 1bc5772..7613d3b 100644
--- a/README.md
+++ b/README.md
@@ -51,8 +51,21 @@ Note that stages are not required in your yaml file - you can also define it wit
 
 ## Configuration
 
-Note that any AWS references (cred, cft, etc...) are currently hard-coded to us-east-1.
+In order to override default configuration, you can supply a `env.js` located next to your `env.yml`.  The format of this file is as follows:
+
+```javascript
+{
+  awsRegion: '<aws-region>',
+  resolvers: {
+    test: value => {
+      // transformation
+      return transformed-value; // or promise
+    }
+  }
+}
+```
 
+Resolvers specified in this file will allow you to expand on the current set of resolvers included in dotenvi (e.g., `env`, `cft`, etc...).  In the above example, the resolver `test` will match all references that look like `${test:some-value}`.
 
 ## Discussion
 
@@ -70,7 +83,6 @@ The reference syntax used in `env.yml` is inspired by [serverless](https://githu
 
 ## Possible Future Work
 
-1. Support for user-defined resolvers (e.g., other than `cft` and `env`).
-2. Allow for `dotenvi` to replace `dotenv`, if desired, by skipping the `.env`-generation step.
-3. Support for references embedded within a configuration value (e.g., `foo-${env:BAR}` --> `foo-bar` if BAR=bar)
-4. Support recursive reference calls (e.g., `${env:${env:FOO}}`)
+1. Allow for `dotenvi` to replace `dotenv`, if desired, by skipping the `.env`-generation step.
+2. Support for references embedded within a configuration value (e.g., `foo-${env:BAR}` --> `foo-bar` if BAR=bar)
+3. Support recursive reference calls (e.g., `${env:${env:FOO}}`)
diff --git a/example/env.js b/example/env.js
new file mode 100644
index 0000000..f7b935b
--- /dev/null
+++ b/example/env.js
@@ -0,0 +1,9 @@
+module.exports = {
+  awsRegion: 'us-east-1',
+  foo: 'ignore me',
+  resolvers: {
+    poop: arg => {
+      return 'poop!'
+    }
+  }
+};
diff --git a/env.yml b/example/env.yml
similarity index 93%
rename from env.yml
rename to example/env.yml
index 0ff55a8..e02fee2 100644
--- a/env.yml
+++ b/example/env.yml
@@ -6,6 +6,7 @@ default_env: &default_env
   CRED_OPTIONAL: 
     value: ${cred:IDSFJKLJ}
     optional: true
+  TEST: ${poop:hello}
 
 sandbox:
   <<: *default_env
diff --git a/package.json b/package.json
index f301d00..82d2b60 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,10 @@
     "dotenvi": "dist/index.js"
   },
   "jest": {
-    "moduleFileExtensions": ["ts", "js"],
+    "moduleFileExtensions": [
+      "ts",
+      "js"
+    ],
     "transform": {
       "^.+\\.(ts|tsx)$": "./node_modules/ts-jest/preprocessor.js"
     },
@@ -26,9 +29,7 @@
     ],
     "testEnvironment": "node",
     "coverageDirectory": "./coverage",
-    "collectCoverage": true,
-    "testMatch": ["**/*.test.(ts|js)"],
-    "testEnvironment": "node"
+    "collectCoverage": true
   },
   "dependencies": {
     "@types/argparse": "^1.0.33",
@@ -54,9 +55,17 @@
     "type": "git",
     "url": "https://github.com/b3ross/dotenvi.git"
   },
-  "keywords": ["dotenv", "yaml", "config", "environment"],
+  "keywords": [
+    "dotenv",
+    "yaml",
+    "config",
+    "environment"
+  ],
   "lint-staged": {
-    "*.{ts,json}": ["prettier --write", "git add"]
+    "*.{ts,json}": [
+      "prettier --write",
+      "git add"
+    ]
   },
   "prettier": {
     "printWidth": 120,
diff --git a/src/index.ts b/src/index.ts
index ec15066..a91c25f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,7 +6,7 @@ import { ArgumentParser } from 'argparse';
 import { Rewriter } from './rewriter';
 import { ResolverMap, Document, InputDocument } from './types';
 import { resolvers } from './resolvers';
-import { writeFile, validateOutput } from './utils';
+import { writeFile, validateOutput, loadConfig } from './utils';
 import { parse } from './inputParser';
 
 const parser = new ArgumentParser();
@@ -14,19 +14,20 @@ parser.addArgument(['-s', '--stage'], {
   help: 'Environment stage',
   dest: 'stage'
 });
-const args = parser.parseArgs();
 
+const args = parser.parseArgs();
+const config = loadConfig();
 
 let document: InputDocument;
 try {
-  // TODO Load external resolvers
   const contents = fs.readFileSync('env.yml', 'utf8')
   document = parse(contents, args.stage);
 } catch (error) {
   console.error(`Could not load yaml ${error.stack}`);
   process.exit(1);
 }
-const rewriter = new Rewriter(resolvers);
+
+const rewriter = new Rewriter(config);
 rewriter.rewrite(document).then(result => {
   const errors = validateOutput(document, result);
   if (errors.length) {
diff --git a/src/resolvers.ts b/src/resolvers.ts
index bfa9745..1026487 100644
--- a/src/resolvers.ts
+++ b/src/resolvers.ts
@@ -1,17 +1,17 @@
 import * as AWS from 'aws-sdk';
-import { CloudFormation, Config } from 'aws-sdk';
+import { CloudFormation } from 'aws-sdk';
 import { DescribeStacksOutput } from 'aws-sdk/clients/cloudformation';
 import { promisify } from 'util';
+const Credstash = require('nodecredstash');
 
-import { ResolverMap } from './types';
+import { ResolverMap, Config } from './types';
 
-const Credstash = require('nodecredstash');
 
 export const resolvers: ResolverMap = {
-  cft: async (argument: string) => {
+  cft: async (argument: string, config: Config) => {
 
     if (!AWS.config.region) {
-      AWS.config.update({ region: 'us-east-1' });
+      AWS.config.update({ region: config.awsRegion });
     }
     const cft = new CloudFormation();
     const parsedArgument = argument.split('.', 2);
@@ -45,8 +45,8 @@ export const resolvers: ResolverMap = {
   constant: async (argument: string) => {
     return argument;
   },
-  cred: async (argument: string) => {
-    const credstash = new Credstash({ awsOpts: { region: 'us-east-1' } });
+  cred: async (argument: string, config: Config) => {
+    const credstash = new Credstash({ awsOpts: { region: config.awsRegion } });
     const promisified = promisify(credstash.getSecret);
     return promisified({ name: argument })
       .catch((error: Error): string => {
diff --git a/src/rewriter.test.js b/src/rewriter.test.js
index 990c940..58b9c6f 100644
--- a/src/rewriter.test.js
+++ b/src/rewriter.test.js
@@ -13,7 +13,7 @@ describe('Rewriter', () => {
       }
     };
 
-    const rewriter = new Rewriter(resolvers);
+    const rewriter = new Rewriter({ resolvers: resolvers });
     return rewriter.rewrite(document).then((output) => {
       expect(output['explicit']).toBe(output['implicit']);
     });
@@ -27,7 +27,7 @@ describe('Rewriter', () => {
       }
     };
 
-    const rewriter = new Rewriter(resolvers);
+    const rewriter = new Rewriter({ resolvers: resolvers });
     return rewriter.rewrite(document).then((output) => {
       expect(output['test']).toBe('hello');
     });
diff --git a/src/rewriter.ts b/src/rewriter.ts
index f362ef5..bb52a25 100644
--- a/src/rewriter.ts
+++ b/src/rewriter.ts
@@ -1,7 +1,7 @@
-import { ResolverMap, Document, InputDocument } from './types';
+import { Document, InputDocument, Config } from './types';
 
 export class Rewriter {
-  constructor(private resolvers: ResolverMap) { }
+  constructor(private config: Config) { }
 
   async rewrite(document: InputDocument): Promise<Document> {
     const variables = Object.keys(document);
@@ -22,14 +22,14 @@ export class Rewriter {
     if (!resolver) {
       throw new Error(`Could not locate resolver for value ${value}`);
     }
-    const result = await resolver(innerValue);
+    const result = await resolver(innerValue, this.config);
     return result;
   }
 
   private getResolver(name: string) {
     if (!name) {
-      return this.resolvers['constant'];
+      return this.config.resolvers['constant'];
     }
-    return this.resolvers[name];
+    return this.config.resolvers[name];
   }
 }
diff --git a/src/types.ts b/src/types.ts
index 85d43f4..b8019a5 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,10 +1,21 @@
-export type ResolverMap = { [name: string]: (arg: string) => Promise<string> };
+export type ResolverFunction = (arg: string, config: Config) => Promise<string>;
+export type ResolverMap = {
+  [name: string]: ResolverFunction
+};
 export type Document = { [name: string]: string }
 
-
 export class InputDocument {
   [name: string]: {
-    value: string,
+    value: string;
     optional?: boolean
   }
 }
+
+export class Config {
+  constructor() {
+    this.resolvers = {};
+    this.awsRegion = 'us-east-1';
+  }
+  awsRegion: string;
+  resolvers: ResolverMap
+}
diff --git a/src/utils.test.js b/src/utils.test.js
index 6efe6da..1635126 100644
--- a/src/utils.test.js
+++ b/src/utils.test.js
@@ -33,7 +33,7 @@ describe('validateOutput', () => {
   it('Does not error if output null and optional', () => {
     const input = {
       'environment': {
-        value: '${env:this_should_not_be_defined',
+        value: '${env:this_should_not_be_defined}',
         optional: true
       }
     };
diff --git a/src/utils.ts b/src/utils.ts
index 6120029..70efcf5 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,5 +1,7 @@
 import * as fs from 'fs';
-import { Document, InputDocument } from './types';
+
+import { Document, InputDocument, Config } from './types';
+import { resolvers } from './resolvers';
 
 export function writeFile(document: { [name: string]: string }) {
   let output = '';
@@ -25,3 +27,17 @@ export function validateOutput(input: InputDocument, output: Document): string[]
   }
   return errors;
 }
+
+
+export function loadConfig(): Config {
+  let config: Config = new Config();
+  if (fs.existsSync(`./env.js`)) {
+    console.info(`Loading configuration from ${process.cwd()}/env.js`);
+    config = require(`${process.cwd()}/env`) as Config;
+    if (!config.resolvers) {
+      config.resolvers = {};
+    }
+  }
+  config.resolvers = Object.assign({}, config.resolvers, resolvers);
+  return config;
+}