diff --git a/lib/less/environment/abstract-file-manager.js b/lib/less/environment/abstract-file-manager.js
index 96b932838..037eac8e5 100644
--- a/lib/less/environment/abstract-file-manager.js
+++ b/lib/less/environment/abstract-file-manager.js
@@ -16,8 +16,12 @@ abstractFileManager.prototype.getPath = function (filename) {
     return filename.slice(0, j + 1);
 };
 
+abstractFileManager.prototype.tryAppendExtension = function(path, ext) {
+    return /(\.[a-z]*$)|([\?;].*)$/.test(path) ? path : path + ext;
+};
+
 abstractFileManager.prototype.tryAppendLessExtension = function(path) {
-    return /(\.[a-z]*$)|([\?;].*)$/.test(path) ? path : path + '.less';
+    return this.tryAppendExtension(path, '.less');
 };
 
 abstractFileManager.prototype.supportsSync = function() {
diff --git a/lib/less/functions/function-caller.js b/lib/less/functions/function-caller.js
index dcce35cfb..d5358b3f5 100644
--- a/lib/less/functions/function-caller.js
+++ b/lib/less/functions/function-caller.js
@@ -1,12 +1,12 @@
-var functionRegistry = require("./function-registry"),
-    Expression = require("../tree/expression");
+var Expression = require("../tree/expression");
 
 var functionCaller = function(name, context, index, currentFileInfo) {
     this.name = name.toLowerCase();
-    this.func = functionRegistry.get(this.name);
     this.index = index;
     this.context = context;
     this.currentFileInfo = currentFileInfo;
+
+    this.func = context.frames[0].functionRegistry.get(this.name);
 };
 functionCaller.prototype.isValid = function() {
     return Boolean(this.func);
diff --git a/lib/less/functions/function-registry.js b/lib/less/functions/function-registry.js
index d39230d1d..bc21bcc8e 100644
--- a/lib/less/functions/function-registry.js
+++ b/lib/less/functions/function-registry.js
@@ -1,18 +1,29 @@
-module.exports = {
-    _data: {},
-    add: function(name, func) {
-        if (this._data.hasOwnProperty(name)) {
-            //TODO warn
+function makeRegistry( base ) {
+    return {
+        _data: {},
+        add: function(name, func) {
+            // precautionary case conversion, as later querying of
+            // the registry by function-caller uses lower case as well.
+            name = name.toLowerCase();
+
+            if (this._data.hasOwnProperty(name)) {
+                //TODO warn
+            }
+            this._data[name] = func;
+        },
+        addMultiple: function(functions) {
+            Object.keys(functions).forEach(
+                function(name) {
+                    this.add(name, functions[name]);
+                }.bind(this));
+        },
+        get: function(name) {
+            return this._data[name] || ( base && base.get( name ));
+        },
+        inherit : function() {
+            return makeRegistry( this );
         }
-        this._data[name] = func;
-    },
-    addMultiple: function(functions) {
-        Object.keys(functions).forEach(
-            function(name) {
-                this.add(name, functions[name]);
-            }.bind(this));
-    },
-    get: function(name) {
-        return this._data[name];
-    }
-};
+    };
+}
+
+module.exports = makeRegistry( null );
\ No newline at end of file
diff --git a/lib/less/import-manager.js b/lib/less/import-manager.js
index 22784d77f..79d2f3fec 100644
--- a/lib/less/import-manager.js
+++ b/lib/less/import-manager.js
@@ -1,5 +1,6 @@
 var contexts = require("./contexts"),
-    Parser = require('./parser/parser');
+    Parser = require('./parser/parser'),
+    FunctionImporter = require('./plugins/function-importer');
 
 module.exports = function(environment) {
 
@@ -65,7 +66,7 @@ module.exports = function(environment) {
         }
 
         if (tryAppendLessExtension) {
-            path = fileManager.tryAppendLessExtension(path);
+            path = fileManager.tryAppendExtension(path, importOptions.plugin ? ".js" : ".less");
         }
 
         var loadFileCallback = function(loadedFile) {
@@ -101,7 +102,11 @@ module.exports = function(environment) {
                 newFileInfo.reference = true;
             }
 
-            if (importOptions.inline) {
+            if (importOptions.plugin) {
+                new FunctionImporter(newEnv, newFileInfo).eval(contents, function (e, root) {
+                    fileParsedFunc(e, root, resolvedFilename);
+                });
+            } else if (importOptions.inline) {
                 fileParsedFunc(null, contents, resolvedFilename);
             } else {
                 new Parser(newEnv, importManager, newFileInfo).parse(contents, function (e, root) {
diff --git a/lib/less/parser/parser.js b/lib/less/parser/parser.js
index df309789b..f6d45eda4 100644
--- a/lib/less/parser/parser.js
+++ b/lib/less/parser/parser.js
@@ -1290,6 +1290,41 @@ var Parser = function Parser(context, imports, fileInfo) {
                 }
             },
 
+            //
+            // A @plugin directive, used to import compiler extensions dynamically.
+            //
+            //     @plugin "lib";
+            //
+            // Depending on our environment, importing is done differently:
+            // In the browser, it's an XHR request, in Node, it would be a
+            // file-system operation. The function used for importing is
+            // stored in `import`, which we pass to the Import constructor.
+            //
+            plugin: function () {
+                var path,
+                    index = parserInput.i,
+                    dir   = parserInput.$re(/^@plugin?\s+/);
+
+                if (dir) {
+                    var options = { plugin : true };
+
+                    if ((path = this.entities.quoted() || this.entities.url())) {
+
+                        if (!parserInput.$(';')) {
+                            parserInput.i = index;
+                            error("missing semi-colon on plugin");
+                        }
+
+                        return new(tree.Import)(path, null, options, index, fileInfo);
+                    }
+                    else
+                    {
+                        parserInput.i = index;
+                        error("malformed plugin statement");
+                    }
+                }
+            },
+
             //
             // A CSS Directive
             //
@@ -1301,7 +1336,7 @@ var Parser = function Parser(context, imports, fileInfo) {
 
                 if (parserInput.currentChar() !== '@') { return; }
 
-                value = this['import']() || this.media();
+                value = this['import']() || this.plugin() || this.media();
                 if (value) {
                     return value;
                 }
diff --git a/lib/less/plugins/function-importer.js b/lib/less/plugins/function-importer.js
new file mode 100644
index 000000000..b863998b2
--- /dev/null
+++ b/lib/less/plugins/function-importer.js
@@ -0,0 +1,35 @@
+var LessError = require('../less-error'),
+    tree = require("../tree");
+
+var FunctionImporter = module.exports = function FunctionImporter(context, fileInfo) {
+    this.fileInfo = fileInfo;
+};
+
+FunctionImporter.prototype.eval = function(contents, callback) {
+    var loaded = {},
+        loader,
+        registry;
+
+    registry = {
+        add: function(name, func) {
+            loaded[name] = func;
+        },
+        addMultiple: function(functions) {
+            Object.keys(functions).forEach(function(name) {
+                loaded[name] = functions[name];
+            });
+        }
+    };
+
+    try {
+        loader = new Function("functions", "tree", "fileInfo", contents);
+        loader(registry, tree, this.fileInfo);
+    } catch(e) {
+        callback(new LessError({
+            message: "Plugin evaluation error: '" + e.name + ': ' + e.message.replace(/["]/g, "'") + "'" ,
+            filename: this.fileInfo.filename
+        }), null );
+    }
+
+    callback(null, { functions: loaded });
+};
diff --git a/lib/less/tree/import.js b/lib/less/tree/import.js
index e88e6dcef..0d3c68079 100644
--- a/lib/less/tree/import.js
+++ b/lib/less/tree/import.js
@@ -50,7 +50,7 @@ Import.prototype.accept = function (visitor) {
         this.features = visitor.visit(this.features);
     }
     this.path = visitor.visit(this.path);
-    if (!this.options.inline && this.root) {
+    if (!this.options.plugin && !this.options.inline && this.root) {
         this.root = visitor.visit(this.root);
     }
 };
@@ -109,7 +109,8 @@ Import.prototype.evalPath = function (context) {
     return path;
 };
 Import.prototype.eval = function (context) {
-    var ruleset, features = this.features && this.features.eval(context);
+    var ruleset, registry,
+        features = this.features && this.features.eval(context);
 
     if (this.skip) {
         if (typeof this.skip === "function") {
@@ -120,7 +121,13 @@ Import.prototype.eval = function (context) {
         }
     }
 
-    if (this.options.inline) {
+    if (this.options.plugin) {
+        registry = context.frames[0] && context.frames[0].functionRegistry;
+        if ( registry && this.root.functions ) {
+            registry.addMultiple( this.root.functions );
+        }
+        return [];
+    } else if (this.options.inline) {
         var contents = new Anonymous(this.root, 0, {filename: this.importedFilename}, true, true);
         return this.features ? new Media([contents], this.features.value) : [contents];
     } else if (this.css) {
diff --git a/lib/less/tree/mixin-definition.js b/lib/less/tree/mixin-definition.js
index b81dd4eb8..9a92ed01b 100644
--- a/lib/less/tree/mixin-definition.js
+++ b/lib/less/tree/mixin-definition.js
@@ -44,6 +44,7 @@ Definition.prototype.evalParams = function (context, mixinEnv, args, evaldArgume
         i, j, val, name, isNamedFound, argIndex, argsLength = 0;
 
     mixinEnv = new contexts.Eval(mixinEnv, [frame].concat(mixinEnv.frames));
+    frame.functionRegistry = context.frames[0].functionRegistry.inherit();
 
     if (args) {
         args = args.slice(0);
diff --git a/lib/less/tree/ruleset.js b/lib/less/tree/ruleset.js
index 9e55c5bf0..ea2948f5b 100644
--- a/lib/less/tree/ruleset.js
+++ b/lib/less/tree/ruleset.js
@@ -4,6 +4,7 @@ var Node = require("./node"),
     Element = require("./element"),
     Paren = require("./paren"),
     contexts = require("../contexts"),
+    globalFunctionRegistry = require("../functions/function-registry"),
     defaultFunc = require("../functions/default"),
     getDebugInfo = require("./debug-info");
 
@@ -66,6 +67,10 @@ Ruleset.prototype.eval = function (context) {
         rules.length = 0;
     }
 
+    // inherit a function registry from the frames stack when possible;
+    // otherwise from the global registry
+    ruleset.functionRegistry = ((context.frames[0] && context.frames[0].functionRegistry) || globalFunctionRegistry).inherit();
+
     // push the current ruleset to the frames stack
     var ctxFrames = context.frames;
     ctxFrames.unshift(ruleset);
diff --git a/test/css/import-plugin-scoped.css b/test/css/import-plugin-scoped.css
new file mode 100644
index 000000000..e42ec6478
--- /dev/null
+++ b/test/css/import-plugin-scoped.css
@@ -0,0 +1,6 @@
+.in-scope {
+  result: PASS;
+}
+.out-of-scope {
+  result: test();
+}
diff --git a/test/css/import-plugin-tiered.css b/test/css/import-plugin-tiered.css
new file mode 100644
index 000000000..7960b9f3f
--- /dev/null
+++ b/test/css/import-plugin-tiered.css
@@ -0,0 +1,6 @@
+.test {
+  result: PASS;
+}
+.test-again {
+  result: PASS;
+}
diff --git a/test/css/import-plugin.css b/test/css/import-plugin.css
new file mode 100644
index 000000000..1c337756a
--- /dev/null
+++ b/test/css/import-plugin.css
@@ -0,0 +1,3 @@
+.test {
+  result: PASS;
+}
diff --git a/test/less/import-plugin-scoped.less b/test/less/import-plugin-scoped.less
new file mode 100644
index 000000000..7c0fa7825
--- /dev/null
+++ b/test/less/import-plugin-scoped.less
@@ -0,0 +1,9 @@
+.in-scope {
+  @plugin "./plugins/test";
+  result : test();
+}
+
+.out-of-scope {
+  result : test();
+}
+
diff --git a/test/less/import-plugin-tiered.less b/test/less/import-plugin-tiered.less
new file mode 100644
index 000000000..eb487738b
--- /dev/null
+++ b/test/less/import-plugin-tiered.less
@@ -0,0 +1,5 @@
+@import "import-plugin";
+
+.test-again {
+  result : test();
+}
\ No newline at end of file
diff --git a/test/less/import-plugin.less b/test/less/import-plugin.less
new file mode 100644
index 000000000..7ee43e30a
--- /dev/null
+++ b/test/less/import-plugin.less
@@ -0,0 +1,5 @@
+@plugin "./plugins/test";
+
+.test {
+  result : test();
+}
\ No newline at end of file
diff --git a/test/less/plugins/test.js b/test/less/plugins/test.js
new file mode 100644
index 000000000..f54ee82b1
--- /dev/null
+++ b/test/less/plugins/test.js
@@ -0,0 +1,4 @@
+
+functions.add("test", function() {
+    return new tree.Anonymous( "PASS" );
+});