diff --git a/__tests__/applyAtRule.test.js b/__tests__/applyAtRule.test.js
index 652b44940ac2..1829a3f9dd0a 100644
--- a/__tests__/applyAtRule.test.js
+++ b/__tests__/applyAtRule.test.js
@@ -1,14 +1,14 @@
 import postcss from 'postcss'
 import plugin from '../src/lib/substituteClassApplyAtRules'
 
-function run(input, opts) {
+function run(input, opts = () => {}) {
     return postcss([plugin(opts)]).process(input)
 }
 
 test("it copies a class's declarations into itself", () => {
     const output = '.a { color: red; } .b { color: red; }'
 
-    return run('.a { color: red; } .b { @apply .a; }', {}).then(result => {
+    return run('.a { color: red; } .b { @apply .a; }').then(result => {
         expect(result.css).toEqual(output)
         expect(result.warnings().length).toBe(0)
     })
@@ -38,16 +38,15 @@ test("it doesn't copy a media query definition into itself", () => {
 
         .b {
             @apply .a;
-        }`,
-        {}
-    ).then(result => {
+        }`)
+    .then(result => {
         expect(result.css).toEqual(output)
         expect(result.warnings().length).toBe(0)
     })
 })
 
 test('it fails if the class does not exist', () => {
-    run('.b { @apply .a; }', {}).catch(error => {
+    run('.b { @apply .a; }').catch(error => {
         expect(error.reason).toEqual('No .a class found.')
     })
 })
diff --git a/__tests__/focusableAtRule.test.js b/__tests__/focusableAtRule.test.js
index 51cdda2131dc..04fb8ba64f8c 100644
--- a/__tests__/focusableAtRule.test.js
+++ b/__tests__/focusableAtRule.test.js
@@ -1,7 +1,7 @@
 import postcss from 'postcss'
 import plugin from '../src/lib/substituteFocusableAtRules'
 
-function run(input, opts = {}) {
+function run(input, opts = () => {}) {
   return postcss([plugin(opts)]).process(input)
 }
 
@@ -18,7 +18,7 @@ test("it adds a focusable variant to each nested class definition", () => {
       .chocolate, .focus\\:chocolate:focus { color: brown; }
   `
 
-  return run(input, {}).then(result => {
+  return run(input).then(result => {
     expect(result.css).toEqual(output)
     expect(result.warnings().length).toBe(0)
   })
diff --git a/__tests__/hoverableAtRule.test.js b/__tests__/hoverableAtRule.test.js
index cd6747bd8995..afcd5096f8df 100644
--- a/__tests__/hoverableAtRule.test.js
+++ b/__tests__/hoverableAtRule.test.js
@@ -1,7 +1,7 @@
 import postcss from 'postcss'
 import plugin from '../src/lib/substituteHoverableAtRules'
 
-function run(input, opts = {}) {
+function run(input, opts = () => {}) {
   return postcss([plugin(opts)]).process(input)
 }
 
@@ -18,7 +18,7 @@ test("it adds a hoverable variant to each nested class definition", () => {
       .chocolate, .hover\\:chocolate:hover { color: brown; }
   `
 
-  return run(input, {}).then(result => {
+  return run(input).then(result => {
     expect(result.css).toEqual(output)
     expect(result.warnings().length).toBe(0)
   })
diff --git a/docs/tailwind.js b/docs/tailwind.js
index 7b45b53b0790..50f51d81414a 100644
--- a/docs/tailwind.js
+++ b/docs/tailwind.js
@@ -1,4 +1,4 @@
-var config = require('../defaultConfig')
+var config = require('../lib/index').defaultConfig()
 
 config.colors = {
   ...config.colors,
diff --git a/src/index.js b/src/index.js
index cc02186bbb6c..f0899fe77f99 100644
--- a/src/index.js
+++ b/src/index.js
@@ -5,6 +5,7 @@ import _ from 'lodash'
 import postcss from 'postcss'
 import stylefmt from 'stylefmt'
 
+import registerConfigAsDependency from './lib/registerConfigAsDependency'
 import substitutePreflightAtRule from './lib/substitutePreflightAtRule'
 import evaluateTailwindFunctions from './lib/evaluateTailwindFunctions'
 import generateUtilities from './lib/generateUtilities'
@@ -15,23 +16,30 @@ import substituteScreenAtRules from './lib/substituteScreenAtRules'
 import substituteClassApplyAtRules from './lib/substituteClassApplyAtRules'
 
 const plugin = postcss.plugin('tailwind', (config) => {
-  if (_.isUndefined(config)) {
-    config = require('../defaultConfig')
+  const plugins = []
+
+  if (! _.isUndefined(config)) {
+    plugins.push(registerConfigAsDependency(path.resolve(config)))
   }
 
-  if (_.isString(config)) {
-    config = require(path.resolve(config))
+  const lazyConfig = () => {
+    if (_.isUndefined(config)) {
+      return require('../defaultConfig')
+    }
+
+    delete require.cache[require.resolve(path.resolve(config))]
+    return require(path.resolve(config))
   }
 
-  return postcss([
-    substitutePreflightAtRule(config),
-    evaluateTailwindFunctions(config),
-    generateUtilities(config),
-    substituteHoverableAtRules(config),
-    substituteFocusableAtRules(config),
-    substituteResponsiveAtRules(config),
-    substituteScreenAtRules(config),
-    substituteClassApplyAtRules(config),
+  return postcss(...plugins, ...[
+    substitutePreflightAtRule(lazyConfig),
+    evaluateTailwindFunctions(lazyConfig),
+    generateUtilities(lazyConfig),
+    substituteHoverableAtRules(lazyConfig),
+    substituteFocusableAtRules(lazyConfig),
+    substituteResponsiveAtRules(lazyConfig),
+    substituteScreenAtRules(lazyConfig),
+    substituteClassApplyAtRules(lazyConfig),
     stylefmt,
   ])
 })
diff --git a/src/lib/evaluateTailwindFunctions.js b/src/lib/evaluateTailwindFunctions.js
index c89e246eeea4..3b2ab34863ad 100644
--- a/src/lib/evaluateTailwindFunctions.js
+++ b/src/lib/evaluateTailwindFunctions.js
@@ -1,7 +1,9 @@
 import _ from 'lodash'
 import functions from 'postcss-functions'
 
-export default function(options) {
+export default function(config) {
+  const options = config()
+
   return functions({
     functions: {
       config: function (path) {
diff --git a/src/lib/generateUtilities.js b/src/lib/generateUtilities.js
index b5c6c5e4a1eb..bf658fcc048a 100644
--- a/src/lib/generateUtilities.js
+++ b/src/lib/generateUtilities.js
@@ -37,8 +37,10 @@ import verticalAlign from '../generators/verticalAlign'
 import visibility from '../generators/visibility'
 import zIndex from '../generators/zIndex'
 
-export default function(options) {
+export default function(config) {
   return function(css) {
+    const options = config()
+
     css.walkAtRules('tailwind', atRule => {
       if (atRule.params === 'utilities') {
         const utilities = _.flatten([
diff --git a/src/lib/registerConfigAsDependency.js b/src/lib/registerConfigAsDependency.js
new file mode 100644
index 000000000000..589db20ed52a
--- /dev/null
+++ b/src/lib/registerConfigAsDependency.js
@@ -0,0 +1,15 @@
+import fs from 'fs'
+
+export default function(configFile) {
+  if (! fs.existsSync(configFile)) {
+    throw new Error(`Specified Tailwind config file "${configFile}" doesn't exist.`)
+  }
+
+  return function (css, opts) {
+    opts.messages = [{
+      type: 'dependency',
+      file: configFile,
+      parent: css.source.input.file,
+    }]
+  }
+}
diff --git a/src/lib/substituteClassApplyAtRules.js b/src/lib/substituteClassApplyAtRules.js
index 7d506d7a2e23..ff3568c4db48 100644
--- a/src/lib/substituteClassApplyAtRules.js
+++ b/src/lib/substituteClassApplyAtRules.js
@@ -9,8 +9,9 @@ function normalizeClassNames(classNames) {
   })
 }
 
-export default postcss.plugin('tailwind-apply', function(css) {
-  return function(css) {
+export default function(config) {
+  return function (css) {
+    const options = config()
     css.walkRules(function(rule) {
       rule.walkAtRules('apply', atRule => {
         const mixins = normalizeClassNames(postcss.list.space(atRule.params))
@@ -42,4 +43,4 @@ export default postcss.plugin('tailwind-apply', function(css) {
       })
     })
   }
-})
+}
diff --git a/src/lib/substituteFocusableAtRules.js b/src/lib/substituteFocusableAtRules.js
index c12aa2b6c8f8..10cf04e2f82f 100644
--- a/src/lib/substituteFocusableAtRules.js
+++ b/src/lib/substituteFocusableAtRules.js
@@ -2,8 +2,10 @@ import _ from 'lodash'
 import postcss from 'postcss'
 import cloneNodes from '../util/cloneNodes'
 
-export default function(options) {
-  return function(css) {
+export default function(config) {
+  return function (css) {
+    const options = config()
+
     css.walkAtRules('focusable', atRule => {
 
       atRule.walkRules(rule => {
diff --git a/src/lib/substituteHoverableAtRules.js b/src/lib/substituteHoverableAtRules.js
index e4d419e2ac13..abe432d70b85 100644
--- a/src/lib/substituteHoverableAtRules.js
+++ b/src/lib/substituteHoverableAtRules.js
@@ -2,8 +2,10 @@ import _ from 'lodash'
 import postcss from 'postcss'
 import cloneNodes from '../util/cloneNodes'
 
-export default function(options) {
-  return function(css) {
+export default function(config) {
+  return function (css) {
+    const options = config()
+
     css.walkAtRules('hoverable', atRule => {
 
       atRule.walkRules(rule => {
diff --git a/src/lib/substitutePreflightAtRule.js b/src/lib/substitutePreflightAtRule.js
index 18478d0ef217..62e01a49a62b 100644
--- a/src/lib/substitutePreflightAtRule.js
+++ b/src/lib/substitutePreflightAtRule.js
@@ -1,8 +1,10 @@
 import fs from 'fs'
 import postcss from 'postcss'
 
-export default function(options) {
+export default function(config) {
   return function (css) {
+    const options = config()
+
     css.walkAtRules('tailwind', atRule => {
       if (atRule.params === 'preflight') {
           atRule.before(postcss.parse(fs.readFileSync(`${__dirname}/../../css/preflight.css`, 'utf8')))
diff --git a/src/lib/substituteResponsiveAtRules.js b/src/lib/substituteResponsiveAtRules.js
index 837035edf8c7..98b306c3f807 100644
--- a/src/lib/substituteResponsiveAtRules.js
+++ b/src/lib/substituteResponsiveAtRules.js
@@ -3,8 +3,10 @@ import postcss from 'postcss'
 import cloneNodes from '../util/cloneNodes'
 import buildMediaQuery from '../util/buildMediaQuery'
 
-export default function({ screens }) {
-  return function(css) {
+
+export default function(config) {
+  return function (css) {
+    const screens = config().screens
     const rules = []
 
     css.walkAtRules('responsive', atRule => {
diff --git a/src/lib/substituteScreenAtRules.js b/src/lib/substituteScreenAtRules.js
index 67d9de91067e..951492e8fb85 100644
--- a/src/lib/substituteScreenAtRules.js
+++ b/src/lib/substituteScreenAtRules.js
@@ -3,8 +3,9 @@ import postcss from 'postcss'
 import cloneNodes from '../util/cloneNodes'
 import buildMediaQuery from '../util/buildMediaQuery'
 
-export default function(options) {
+export default function(config) {
   return function(css) {
+    const options = config()
     const rules = []
 
     css.walkAtRules('screen', atRule => {