diff --git a/README.md b/README.md
index 3815fc94..d14fe299 100644
--- a/README.md
+++ b/README.md
@@ -28,8 +28,8 @@ tool for [Node.js](https://nodejs.org/) and [io.js](https://iojs.org/) with a
 library of rules to enforce standards and consistency for Markdown files. It
 was inspired by - and heavily influenced by - Mark Harrison's
 [markdownlint](https://github.com/mivok/markdownlint) for
-[Ruby](https://www.ruby-lang.org/). The rules, rule documentation, and test
-cases come directly from that project.
+[Ruby](https://www.ruby-lang.org/). The initial rules, rule documentation, and
+test cases came directly from that project.
 
 ### Related
 
@@ -142,11 +142,13 @@ space * in * emphasis <!-- markdownlint-disable --> <!-- markdownlint-enable -->
 
 ## API
 
+### Linting
+
 Standard asynchronous interface:
 
 ```js
 /**
- * Lint specified Markdown files according to configurable rules.
+ * Lint specified Markdown files.
  *
  * @param {Object} options Configuration options.
  * @param {Function} callback Callback (err, result) function.
@@ -159,7 +161,7 @@ Synchronous interface (for build scripts, etc.):
 
 ```js
 /**
- * Lint specified Markdown files according to configurable rules.
+ * Lint specified Markdown files synchronously.
  *
  * @param {Object} options Configuration options.
  * @returns {Object} Result object.
@@ -167,13 +169,13 @@ Synchronous interface (for build scripts, etc.):
 function markdownlint.sync(options) { ... }
 ```
 
-### options
+#### options
 
 Type: `Object`
 
 Configures the function.
 
-#### options.files
+##### options.files
 
 Type: `Array` of `String`
 
@@ -185,7 +187,7 @@ responsibility.
 
 Example: `[ "one.md", "dir/two.md" ]`
 
-#### options.strings
+##### options.strings
 
 Type: `Object` mapping `String` to `String`
 
@@ -204,7 +206,7 @@ Example:
 }
 ```
 
-#### options.frontMatter
+##### options.frontMatter
 
 Type: `RegExp`
 
@@ -232,7 +234,7 @@ title: Title
 ---
 ```
 
-#### options.config
+##### options.config
 
 Type: `Object` mapping `String` to `Boolean | Object`
 
@@ -277,7 +279,46 @@ See the [style](style) directory for more samples.
 See [markdownlint-config-schema.json](schema/markdownlint-config-schema.json)
 for the [JSON Schema](http://json-schema.org/) of the `options.config` object.
 
-#### options.resultVersion
+For more advanced scenarios, styles can reference and extend other styles. The
+`readConfig` and `readConfigSync` functions can be used to read such styles.
+
+For example, assuming a `base.json` configuration file:
+
+```json
+{
+  "default": true
+}
+```
+
+And a `custom.json` configuration file:
+
+```json
+{
+  "extends": "base.json",
+  "line-length": false
+}
+```
+
+Then code like the following:
+
+```js
+var options = {
+  "config": markdownlint.readConfigSync("./custom.json")
+};
+```
+
+Merges `custom.json` and `base.json` and is equivalent to:
+
+```js
+var options = {
+  "config": {
+    "default": true,
+    "line-length": false
+  }
+};
+```
+
+##### options.resultVersion
 
 Type: `Number`
 
@@ -291,13 +332,13 @@ Passing a `resultVersion` of `1` corresponds to a more detailed format where eac
 error includes information about the line number, rule name, alias, description,
 as well as any additional detail or context that is available.
 
-### callback
+#### callback
 
 Type: `Function` taking (`Error`, `Object`)
 
 Standard completion callback.
 
-### result
+#### result
 
 Type: `Object`
 
@@ -305,6 +346,61 @@ Call `result.toString()` for convenience or see below for an example of the
 structure of the `result` object. Passing the value `true` to `toString()`
 uses rule aliases (ex: `no-hard-tabs`) instead of names (ex: `MD010`).
 
+### Config
+
+The `options.config` configuration object is simple and can be loaded as JSON
+in many cases. To take advantage of shared configuration where one file `extends`
+another, the following functions are useful.
+
+Asynchronous interface:
+
+```js
+/**
+ * Read specified configuration file.
+ *
+ * @param {String} file Configuration file name/path.
+ * @param {Function} callback Callback (err, result) function.
+ * @returns {void}
+ */
+function readConfig(file, callback) { ... }
+```
+
+Synchronous interface:
+
+```js
+/**
+ * Read specified configuration file synchronously.
+ *
+ * @param {String} file Configuration file name/path.
+ * @returns {Object} Configuration object.
+ */
+function readConfigSync(file) { ... }
+```
+
+#### file
+
+Type: `String`
+
+Location of JSON configuration file to read.
+
+The `file` is resolved relative to the current working directory. If an `extends`
+key is present once read, its value will be resolved as a path relative to `file`
+and loaded recursively. Settings from a file referenced by `extends` are applied
+first, then those of `file` are applied on top (overriding any of the same keys
+appearing in the referenced file).
+
+#### callback
+
+Type: `Function` taking (`Error`, `Object`)
+
+Standard completion callback.
+
+#### result
+
+Type: `Object`
+
+Configuration object.
+
 ## Usage
 
 Invoke `markdownlint` and use the `result` object's `toString` method:
diff --git a/lib/markdownlint.js b/lib/markdownlint.js
index c714402b..fd37297e 100644
--- a/lib/markdownlint.js
+++ b/lib/markdownlint.js
@@ -1,6 +1,7 @@
 "use strict";
 
 var fs = require("fs");
+var path = require("path");
 var md = require("markdown-it")({ "html": true });
 var rules = require("./rules");
 var shared = require("./shared");
@@ -329,7 +330,7 @@ function markdownlintSynchronousCallback() {
 }
 
 /**
- * Lint specified Markdown files according to configurable rules.
+ * Lint specified Markdown files.
  *
  * @param {Object} options Configuration options.
  * @param {Function} callback Callback (err, result) function.
@@ -387,7 +388,7 @@ function markdownlint(options, callback) {
 }
 
 /**
- * Lint specified Markdown files according to configurable rules.
+ * Lint specified Markdown files synchronously.
  *
  * @param {Object} options Configuration options.
  * @returns {Object} Result object.
@@ -396,6 +397,63 @@ function markdownlintSync(options) {
   return markdownlint(options, markdownlintSynchronousCallback);
 }
 
+/**
+ * Read specified configuration file.
+ *
+ * @param {String} file Configuration file name/path.
+ * @param {Function} callback Callback (err, result) function.
+ * @returns {void}
+ */
+function readConfig(file, callback) {
+  // Read file
+  fs.readFile(file, shared.utf8Encoding, function handleFile(err, content) {
+    if (err) {
+      return callback(err);
+    }
+    // Parse file
+    var config = null;
+    try {
+      config = JSON.parse(content);
+    } catch (ex) {
+      return callback(ex);
+    }
+    if (config.extends) {
+      // Extend configuration
+      var extendsFile = path.resolve(path.dirname(file), config.extends);
+      readConfig(extendsFile, function handleConfig(errr, extendsConfig) {
+        if (errr) {
+          return callback(errr);
+        }
+        delete config.extends;
+        callback(null, shared.assign(extendsConfig, config));
+      });
+    } else {
+      callback(null, config);
+    }
+  });
+}
+
+/**
+ * Read specified configuration file synchronously.
+ *
+ * @param {String} file Configuration file name/path.
+ * @returns {Object} Configuration object.
+ */
+function readConfigSync(file) {
+  // Parse file
+  var config = JSON.parse(fs.readFileSync(file, shared.utf8Encoding));
+  if (config.extends) {
+    // Extend configuration
+    config = shared.assign(
+      readConfigSync(path.resolve(path.dirname(file), config.extends)),
+      config);
+    delete config.extends;
+  }
+  return config;
+}
+
 // Export a/synchronous APIs
 module.exports = markdownlint;
 module.exports.sync = markdownlintSync;
+module.exports.readConfig = readConfig;
+module.exports.readConfigSync = readConfigSync;
diff --git a/schema/build-config-schema.js b/schema/build-config-schema.js
index 7de4b4c5..6ed88199 100644
--- a/schema/build-config-schema.js
+++ b/schema/build-config-schema.js
@@ -13,6 +13,11 @@ var schema = {
       "description": "Default state for all rules",
       "type": "boolean",
       "default": true
+    },
+    "extends": {
+      "description": "Path to configuration file to extend",
+      "type": "string",
+      "default": null
     }
   },
   "additionalProperties": false
diff --git a/schema/markdownlint-config-schema.json b/schema/markdownlint-config-schema.json
index c43e6538..b6da4001 100644
--- a/schema/markdownlint-config-schema.json
+++ b/schema/markdownlint-config-schema.json
@@ -7,6 +7,11 @@
       "type": "boolean",
       "default": true
     },
+    "extends": {
+      "description": "Path to configuration file to extend",
+      "type": "string",
+      "default": null
+    },
     "MD001": {
       "description": "MD001/header-increment - Header levels should only increment by one level at a time",
       "type": "boolean",
diff --git a/test/config-child.json b/test/config-child.json
new file mode 100644
index 00000000..f56f00bf
--- /dev/null
+++ b/test/config-child.json
@@ -0,0 +1,4 @@
+{
+  "no-hard-tabs": false,
+  "whitespace": false
+}
diff --git a/test/config-grandparent.json b/test/config-grandparent.json
new file mode 100644
index 00000000..4a45360c
--- /dev/null
+++ b/test/config-grandparent.json
@@ -0,0 +1,6 @@
+{
+  "extends": "config-parent.json",
+  "MD003": { "style": "atx_closed" },
+  "MD007": { "indent": 2 },
+  "no-hard-tabs": false
+}
diff --git a/test/config-parent.json b/test/config-parent.json
new file mode 100644
index 00000000..172b646c
--- /dev/null
+++ b/test/config-parent.json
@@ -0,0 +1,7 @@
+{
+  "extends": "config-child.json",
+  "MD003": false,
+  "MD007": { "indent": 4 },
+  "no-hard-tabs": true,
+  "line-length": { "line_length": 200 }
+}
diff --git a/test/config/config-badchildfile.json b/test/config/config-badchildfile.json
new file mode 100644
index 00000000..774a3b8a
--- /dev/null
+++ b/test/config/config-badchildfile.json
@@ -0,0 +1,4 @@
+{
+  "extends": "config-badfile.json",
+  "default": true
+}
diff --git a/test/config/config-badchildjson.json b/test/config/config-badchildjson.json
new file mode 100644
index 00000000..551ecb41
--- /dev/null
+++ b/test/config/config-badchildjson.json
@@ -0,0 +1,4 @@
+{
+  "extends": "config-badjson.json",
+  "default": true
+}
diff --git a/test/config/config-badjson.json b/test/config/config-badjson.json
new file mode 100644
index 00000000..9f37b62b
--- /dev/null
+++ b/test/config/config-badjson.json
@@ -0,0 +1,3 @@
+{
+  bad json
+}
diff --git a/test/markdownlint-test.js b/test/markdownlint-test.js
index f73cbe55..4e87daf1 100644
--- a/test/markdownlint-test.js
+++ b/test/markdownlint-test.js
@@ -87,7 +87,7 @@ module.exports.projectFiles = function projectFiles(test) {
   };
   markdownlint(options, function callback(err, actual) {
     test.ifError(err);
-    var expected = { "README.md": {} };
+    var expected = { "README.md": { "MD024": [ 392, 398 ] } };
     test.deepEqual(actual, expected, "Issue(s) with project files.");
     test.done();
   });
@@ -782,14 +782,19 @@ module.exports.readmeHeaders = function readmeHeaders(test) {
           "## Tags",
           "## Configuration",
           "## API",
-          "### options",
-          "#### options.files",
-          "#### options.strings",
-          "#### options.frontMatter",
-          "#### options.config",
-          "#### options.resultVersion",
-          "### callback",
-          "### result",
+          "### Linting",
+          "#### options",
+          "##### options.files",
+          "##### options.strings",
+          "##### options.frontMatter",
+          "##### options.config",
+          "##### options.resultVersion",
+          "#### callback",
+          "#### result",
+          "### Config",
+          "#### file",
+          "#### callback",
+          "#### result",
           "## Usage",
           "## Browser",
           "## History"
@@ -798,7 +803,7 @@ module.exports.readmeHeaders = function readmeHeaders(test) {
     }
   }, function callback(err, result) {
     test.ifError(err);
-    var expected = { "README.md": {} };
+    var expected = { "README.md": { "MD024": [ 392, 398 ] } };
     test.deepEqual(result, expected, "Unexpected issues.");
     test.done();
   });
@@ -825,7 +830,7 @@ module.exports.filesArrayAsString = function filesArrayAsString(test) {
     "config": { "MD013": { "line_length": 150 } }
   }, function callback(err, actual) {
     test.ifError(err);
-    var expected = { "README.md": {} };
+    var expected = { "README.md": { "MD024": [ 392, 398 ] } };
     test.deepEqual(actual, expected, "Unexpected issues.");
     test.done();
   });
@@ -1109,3 +1114,166 @@ module.exports.trimPolyfills = function trimPolyfills(test) {
   });
   test.done();
 };
+
+module.exports.configSingle = function configSingle(test) {
+  test.expect(2);
+  markdownlint.readConfig("./test/config-child.json",
+    function callback(err, actual) {
+      test.ifError(err);
+      var expected = require("./config-child.json");
+      test.deepEqual(actual, expected, "Config object not correct.");
+      test.done();
+    });
+};
+
+module.exports.configAbsolute = function configAbsolute(test) {
+  test.expect(2);
+  markdownlint.readConfig(path.join(__dirname, "config-child.json"),
+    function callback(err, actual) {
+      test.ifError(err);
+      var expected = require("./config-child.json");
+      test.deepEqual(actual, expected, "Config object not correct.");
+      test.done();
+    });
+};
+
+module.exports.configMultiple = function configMultiple(test) {
+  test.expect(2);
+  markdownlint.readConfig("./test/config-grandparent.json",
+    function callback(err, actual) {
+      test.ifError(err);
+      var expected = shared.assign(shared.assign(shared.assign({},
+        require("./config-child.json")),
+        require("./config-parent.json")),
+        require("./config-grandparent.json"));
+      delete expected.extends;
+      test.deepEqual(actual, expected, "Config object not correct.");
+      test.done();
+    });
+};
+
+module.exports.configBadFile = function configBadFile(test) {
+  test.expect(4);
+  markdownlint.readConfig("./test/config/config-badfile.json",
+    function callback(err, result) {
+      test.ok(err, "Did not get an error for bad file.");
+      test.ok(err instanceof Error, "Error not instance of Error.");
+      test.equal(err.code, "ENOENT", "Error code for bad file not ENOENT.");
+      test.ok(!result, "Got result for bad file.");
+      test.done();
+    });
+};
+
+module.exports.configBadChildFile = function configBadChildFile(test) {
+  test.expect(4);
+  markdownlint.readConfig("./test/config/config-badchildfile.json",
+    function callback(err, result) {
+      test.ok(err, "Did not get an error for bad child file.");
+      test.ok(err instanceof Error, "Error not instance of Error.");
+      test.equal(err.code, "ENOENT",
+        "Error code for bad child file not ENOENT.");
+      test.ok(!result, "Got result for bad child file.");
+      test.done();
+    });
+};
+
+module.exports.configBadJson = function configBadJson(test) {
+  test.expect(3);
+  markdownlint.readConfig("./test/config/config-badjson.json",
+    function callback(err, result) {
+      test.ok(err, "Did not get an error for bad JSON.");
+      test.ok(err instanceof Error, "Error not instance of Error.");
+      test.ok(!result, "Got result for bad JSON.");
+      test.done();
+    });
+};
+
+module.exports.configBadChildJson = function configBadChildJson(test) {
+  test.expect(3);
+  markdownlint.readConfig("./test/config/config-badchildjson.json",
+    function callback(err, result) {
+      test.ok(err, "Did not get an error for bad child JSON.");
+      test.ok(err instanceof Error, "Error not instance of Error.");
+      test.ok(!result, "Got result for bad child JSON.");
+      test.done();
+    });
+};
+
+module.exports.configSingleSync = function configSingleSync(test) {
+  test.expect(1);
+  var actual = markdownlint.readConfigSync("./test/config-child.json");
+  var expected = require("./config-child.json");
+  test.deepEqual(actual, expected, "Config object not correct.");
+  test.done();
+};
+
+module.exports.configAbsoluteSync = function configAbsoluteSync(test) {
+  test.expect(1);
+  var actual = markdownlint.readConfigSync(
+    path.join(__dirname, "config-child.json"));
+  var expected = require("./config-child.json");
+  test.deepEqual(actual, expected, "Config object not correct.");
+  test.done();
+};
+
+module.exports.configMultipleSync = function configMultipleSync(test) {
+  test.expect(1);
+  var actual = markdownlint.readConfigSync("./test/config-grandparent.json");
+  var expected = shared.assign(shared.assign(shared.assign({},
+    require("./config-child.json")),
+    require("./config-parent.json")),
+    require("./config-grandparent.json"));
+  delete expected.extends;
+  test.deepEqual(actual, expected, "Config object not correct.");
+  test.done();
+};
+
+module.exports.configBadFileSync = function configBadFileSync(test) {
+  test.expect(4);
+  test.throws(function badFileCall() {
+    markdownlint.readConfigSync("./test/config-badfile.json");
+  }, function testError(err) {
+    test.ok(err, "Did not get an error for bad file.");
+    test.ok(err instanceof Error, "Error not instance of Error.");
+    test.equal(err.code, "ENOENT", "Error code for bad file not ENOENT.");
+    return true;
+  }, "Did not get exception for bad file.");
+  test.done();
+};
+
+module.exports.configBadChildFileSync = function configBadChildFileSync(test) {
+  test.expect(4);
+  test.throws(function badChildFileCall() {
+    markdownlint.readConfigSync("./test/config-badfile.json");
+  }, function testError(err) {
+    test.ok(err, "Did not get an error for bad child file.");
+    test.ok(err instanceof Error, "Error not instance of Error.");
+    test.equal(err.code, "ENOENT", "Error code for bad child file not ENOENT.");
+    return true;
+  }, "Did not get exception for bad child file.");
+  test.done();
+};
+
+module.exports.configBadJsonSync = function configBadJsonSync(test) {
+  test.expect(3);
+  test.throws(function badJsonCall() {
+    markdownlint.readConfigSync("./test/config-badjson.json");
+  }, function testError(err) {
+    test.ok(err, "Did not get an error for bad JSON.");
+    test.ok(err instanceof Error, "Error not instance of Error.");
+    return true;
+  }, "Did not get exception for bad JSON.");
+  test.done();
+};
+
+module.exports.configBadChildJsonSync = function configBadChildJsonSync(test) {
+  test.expect(3);
+  test.throws(function badChildJsonCall() {
+    markdownlint.readConfigSync("./test/config-badchildjson.json");
+  }, function testError(err) {
+    test.ok(err, "Did not get an error for bad child JSON.");
+    test.ok(err instanceof Error, "Error not instance of Error.");
+    return true;
+  }, "Did not get exception for bad child JSON.");
+  test.done();
+};