diff --git a/CHANGELOG.md b/CHANGELOG.md
index 486dacfc..2d7df42d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+## [6.2.0] - 2018-12-03
+
+### Added
+
+- Support preload configuration via environment variables ([#351](https://github.com/motdotla/dotenv/issues/351))
+
 ## [6.1.0] - 2018-10-08
 
 ### Added
@@ -32,7 +38,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Removed
 
-- Testing aginst Node v7
+- Testing against Node v7
 
 
 ## [4.0.0] - 2016-12-23
@@ -98,7 +104,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Removed
 - support for multiple `.env` files. should always use one `.env` file for the current environment
 
-[Unreleased]: https://github.com/motdotla/dotenv/compare/v6.1.0...HEAD
+[Unreleased]: https://github.com/motdotla/dotenv/compare/v6.2.0...HEAD
+[6.2.0]: https://github.com/motdotla/dotenv/compare/v6.1.0...v6.2.0
 [6.1.0]: https://github.com/motdotla/dotenv/compare/v6.0.0...v6.1.0
 [6.0.0]: https://github.com/motdotla/dotenv/compare/v5.0.0...v6.0.0
 [5.0.0]: https://github.com/motdotla/dotenv/compare/v4.0.0...v5.0.0
diff --git a/README.md b/README.md
index 034fc52d..cb4148b3 100644
--- a/README.md
+++ b/README.md
@@ -53,7 +53,7 @@ db.connect({
 
 ### Preload
 
-You can use the `--require` (`-r`) command line option to preload dotenv. By doing this, you do not need to require and load dotenv in your application code. This is the preferred approach when using `import` instead of `require`.
+You can use the `--require` (`-r`) [command line option](https://nodejs.org/api/cli.html#cli_r_require_module) to preload dotenv. By doing this, you do not need to require and load dotenv in your application code. This is the preferred approach when using `import` instead of `require`.
 
 ```bash
 $ node -r dotenv/config your_script.js
@@ -65,6 +65,16 @@ The configuration options below are supported as command line arguments in the f
 $ node -r dotenv/config your_script.js dotenv_config_path=/custom/path/to/your/env/vars
 ```
 
+Additionally, you can use environment variables to set configuration options. Command line arguments will precede these.
+
+```bash
+$ DOTENV_CONFIG_<OPTION>=value node -r dotenv/config your_script.js
+```
+
+```bash
+$ DOTENV_CONFIG_ENCODING=base64 node -r dotenv/config your_script.js dotenv_config_path=/custom/path/to/.env
+```
+
 ## Config
 
 _Alias: `load`_
@@ -212,9 +222,7 @@ variableExpansion(myEnv)
 
 ### What about variable expansion?
 
-For `dotenv@2.x.x`: Use [dotenv-expand](https://github.com/motdotla/dotenv-expand).
-
-For `dotenv@1.x.x`: We haven't been presented with a compelling use case for expanding variables and believe it leads to env vars that are not "fully orthogonal" as [The Twelve-Factor App](http://12factor.net/config) outlines.<sup>[[1](https://github.com/motdotla/dotenv/issues/39)][[2](https://github.com/motdotla/dotenv/pull/97)]</sup> Please open an issue if you have a compelling use case.
+Try [dotenv-expand](https://github.com/motdotla/dotenv-expand)
 
 ### How do I use dotenv with `import`?
 
diff --git a/config.js b/config.js
index 77641220..c7e6447f 100644
--- a/config.js
+++ b/config.js
@@ -2,6 +2,10 @@
 
 (function () {
   require('./lib/main').config(
-    require('./lib/cli-options')(process.argv)
+    Object.assign(
+      {},
+      require('./lib/env-options'),
+      require('./lib/cli-options')(process.argv)
+    )
   )
 })()
diff --git a/lib/env-options.js b/lib/env-options.js
new file mode 100644
index 00000000..e602202f
--- /dev/null
+++ b/lib/env-options.js
@@ -0,0 +1,18 @@
+/* @flow */
+
+// ../config.js accepts options via environment variables
+const options = {}
+
+if (process.env.DOTENV_CONFIG_ENCODING) {
+  options.encoding = process.env.DOTENV_CONFIG_ENCODING
+}
+
+if (process.env.DOTENV_CONFIG_PATH) {
+  options.path = process.env.DOTENV_CONFIG_PATH
+}
+
+if (process.env.DOTENV_CONFIG_DEBUG) {
+  options.debug = process.env.DOTENV_CONFIG_DEBUG
+}
+
+module.exports = options
diff --git a/package-lock.json b/package-lock.json
index 8295eddc..4f7ec60d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "dotenv",
-  "version": "6.2.0-rc1",
+  "version": "6.2.0-0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -428,6 +428,12 @@
         "callsites": "^0.2.0"
       }
     },
+    "callsite": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/callsite/-/callsite-1.0.0.tgz",
+      "integrity": "sha1-KAOY5dZkvXQDi28JBRU+borxvCA=",
+      "dev": true
+    },
     "callsites": {
       "version": "0.2.0",
       "resolved": "https://registry.npmjs.org/callsites/-/callsites-0.2.0.tgz",
@@ -671,6 +677,15 @@
       "integrity": "sha1-IwdjLUwEOCuN+KMvcLiVBG1SdF8=",
       "dev": true
     },
+    "decache": {
+      "version": "4.5.0",
+      "resolved": "https://registry.npmjs.org/decache/-/decache-4.5.0.tgz",
+      "integrity": "sha512-XLFg1feTf4cZ5MBxJWEkvQTo7m5PiYF7oNkCGT/ibytYOUGucLBr+WZB+cbyK+6Z4wpazFbrmoUAU0+/6DC/2w==",
+      "dev": true,
+      "requires": {
+        "callsite": "^1.0.0"
+      }
+    },
     "decode-uri-component": {
       "version": "0.2.0",
       "resolved": "https://registry.npmjs.org/decode-uri-component/-/decode-uri-component-0.2.0.tgz",
diff --git a/package.json b/package.json
index 2f7d19de..99100e71 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "dotenv",
-  "version": "6.2.0-rc1",
+  "version": "6.2.0-0",
   "description": "Loads environment variables from .env file",
   "main": "lib/main.js",
   "scripts": {
@@ -26,6 +26,7 @@
   "readmeFilename": "README.md",
   "license": "BSD-2-Clause",
   "devDependencies": {
+    "decache": "^4.5.0",
     "flow-bin": "^0.84.0",
     "sinon": "^6.3.5",
     "standard": "^12.0.1",
diff --git a/tests/test-config-cli.js b/tests/test-config-cli.js
index c5281165..c7ad3d02 100644
--- a/tests/test-config-cli.js
+++ b/tests/test-config-cli.js
@@ -3,29 +3,66 @@
 const cp = require('child_process')
 const path = require('path')
 
-const test = require('tap').test
+const t = require('tap')
 
-const nodeBinary = process.argv[0]
+function spawn (cmd, options = {}) {
+  const { stdout } = cp.spawnSync(
+    process.argv[0], // node binary
+    cmd,
+    Object.assign(
+      {},
+      {
+        cwd: path.resolve(__dirname, '..'),
+        timeout: 5000,
+        encoding: 'utf8'
+      },
+      options
+    )
+  )
 
-test('config preload loads .env', t => {
-  t.plan(1)
+  return stdout
+}
 
-  const { stdout } = cp.spawnSync(
-    nodeBinary,
+t.plan(3)
+
+// dotenv/config enables preloading
+t.equal(
+  spawn([
+    '-r',
+    '../config',
+    '-e',
+    'console.log(process.env.BASIC)',
+    'dotenv_config_encoding=utf8',
+    'dotenv_config_path=./tests/.env'
+  ]),
+  'basic\n'
+)
+
+// dotenv/config supports configuration via environment variables
+t.equal(
+  spawn(['-r', '../config', '-e', 'console.log(process.env.BASIC)'], {
+    env: {
+      DOTENV_CONFIG_PATH: './tests/.env'
+    }
+  }),
+  'basic\n'
+)
+
+// dotenv/config takes CLI configuration over environment variables
+t.equal(
+  spawn(
     [
       '-r',
       '../config',
       '-e',
       'console.log(process.env.BASIC)',
-      'dotenv_config_encoding=utf8',
       'dotenv_config_path=./tests/.env'
     ],
     {
-      cwd: path.resolve(__dirname, '..'),
-      timeout: 5000,
-      encoding: 'utf8'
+      env: {
+        DOTENV_CONFIG_PATH: '/tmp/dne/path/.env.should.break'
+      }
     }
-  )
-
-  t.equal(stdout, 'basic\n')
-})
+  ),
+  'basic\n'
+)
diff --git a/tests/test-config.js b/tests/test-config.js
index 8f883c6b..18a07ca0 100644
--- a/tests/test-config.js
+++ b/tests/test-config.js
@@ -11,6 +11,8 @@ const mockParseResponse = { test: 'foo' }
 let readFileSyncStub
 let parseStub
 
+t.plan(9)
+
 t.beforeEach(done => {
   readFileSyncStub = sinon.stub(fs, 'readFileSync').returns('test=foo')
   parseStub = sinon.stub(dotenv, 'parse').returns(mockParseResponse)
@@ -81,18 +83,21 @@ t.test('does not write over keys already in process.env', ct => {
   ct.equal(process.env.test, existing)
 })
 
-t.test('does not write over keys already in process.env if the key has a falsy value', ct => {
-  ct.plan(2)
-
-  const existing = ''
-  process.env.test = existing
-  // 'foo' returned as value in `beforeEach`. should keep this ''
-  const env = dotenv.config()
-
-  ct.equal(env.parsed && env.parsed.test, mockParseResponse.test)
-  // NB: process.env.test becomes undefined on Windows
-  ct.notOk(process.env.test)
-})
+t.test(
+  'does not write over keys already in process.env if the key has a falsy value',
+  ct => {
+    ct.plan(2)
+
+    const existing = ''
+    process.env.test = existing
+    // 'foo' returned as value in `beforeEach`. should keep this ''
+    const env = dotenv.config()
+
+    ct.equal(env.parsed && env.parsed.test, mockParseResponse.test)
+    // NB: process.env.test becomes undefined on Windows
+    ct.notOk(process.env.test)
+  }
+)
 
 t.test('returns parsed object', ct => {
   ct.plan(2)
diff --git a/tests/test-env-options.js b/tests/test-env-options.js
new file mode 100644
index 00000000..e04f4089
--- /dev/null
+++ b/tests/test-env-options.js
@@ -0,0 +1,50 @@
+/* @flow */
+
+const t = require('tap')
+const decache = require('decache')
+
+// warm cache
+require('../lib/env-options')
+
+// preserve existing env
+const e = process.env.DOTENV_CONFIG_ENCODING
+const p = process.env.DOTENV_CONFIG_PATH
+const d = process.env.DOTENV_CONFIG_DEBUG
+
+// get fresh object for each test
+function options () {
+  decache('../lib/env-options.js')
+  return require('../lib/env-options')
+}
+
+function testOption (envVar, tmpVal, expect) {
+  delete process.env[envVar]
+  process.env[envVar] = tmpVal
+
+  t.same(options(), expect)
+
+  delete process.env[envVar]
+}
+
+t.plan(4)
+
+// returns empty object when no options set in process.env
+delete process.env.DOTENV_CONFIG_ENCODING
+delete process.env.DOTENV_CONFIG_PATH
+delete process.env.DOTENV_CONFIG_DEBUG
+
+t.same(options(), {})
+
+// sets encoding option
+testOption('DOTENV_CONFIG_ENCODING', 'base64', { encoding: 'base64' })
+
+// sets path option
+testOption('DOTENV_CONFIG_PATH', '~/.env.test', { path: '~/.env.test' })
+
+// sets debug option
+testOption('DOTENV_CONFIG_DEBUG', 'true', { debug: 'true' })
+
+// restore existing env
+process.env.DOTENV_CONFIG_ENCODING = e
+process.env.DOTENV_CONFIG_PATH = p
+process.env.DOTENV_CONFIG_DEBUG = d