diff --git a/IPython/html/static/services/kernels/comm.js b/IPython/html/static/services/kernels/comm.js
index 91f3dc826..f25517b82 100644
--- a/IPython/html/static/services/kernels/comm.js
+++ b/IPython/html/static/services/kernels/comm.js
@@ -65,20 +65,40 @@ define([
     
     CommManager.prototype.comm_open = function (msg) {
         var content = msg.content;
-        var f = this.targets[content.target_name];
-        if (f === undefined) {
-            console.log("No such target registered: ", content.target_name);
-            console.log("Available targets are: ", this.targets);
-            return;
-        }
-        var comm = new Comm(content.target_name, content.comm_id);
-        this.register_comm(comm);
-        try {
-            f(comm, msg);
-        } catch (e) {
-            console.log("Exception opening new comm:", e, e.stack, msg);
-            comm.close();
-            this.unregister_comm(comm);
+        var that = this;
+        
+        var instantiate_comm = function(target) {
+            var comm = new Comm(content.target_name, content.comm_id);
+            that.register_comm(comm);
+            try {
+                target(comm, msg);
+            } catch (e) {
+                console.log("Exception opening new comm:", e, e.stack, msg);
+                comm.close();
+                that.unregister_comm(comm);
+            }
+        };
+
+        if (content.target_module) {
+            // Load requirejs module for comm target
+            require([content.target_module], function(mod) {
+                var target = mod[content.target_name];
+                if (target !== undefined) {
+                    instantiate_comm(target)
+                } else {
+                    console.log("Comm target " + content.target_name + 
+                        " not found in module " + content.target_module);
+                }
+            }, function(err) { console.log(err); });
+        } else {
+            // No requirejs module specified: look for target in registry
+            var f = this.targets[content.target_name];
+            if (f === undefined) {
+                console.log("No such target registered: ", content.target_name);
+                console.log("Available targets are: ", this.targets);
+                return;
+            }
+            instantiate_comm(f)
         }
     };
     
diff --git a/IPython/html/static/widgets/js/manager.js b/IPython/html/static/widgets/js/manager.js
index dd3472c52..944effd5a 100644
--- a/IPython/html/static/widgets/js/manager.js
+++ b/IPython/html/static/widgets/js/manager.js
@@ -188,13 +188,33 @@ define([
     WidgetManager.prototype._handle_comm_open = function (comm, msg) {
         // Handle when a comm is opened.
         var that = this;
-        var model_id = comm.comm_id;
+        
+        var instantiate_model = function(ModelType) {
+            var model_id = comm.comm_id;
+            var widget_model = new ModelType(that, model_id, comm);
+            widget_model.on('comm:close', function () {
+              delete that._models[model_id];
+            });
+            that._models[model_id] = widget_model;
+        };
+        
         var widget_type_name = msg.content.data.model_name;
-        var widget_model = new WidgetManager._model_types[widget_type_name](this, model_id, comm);
-        widget_model.on('comm:close', function () {
-          delete that._models[model_id];
-        });
-        this._models[model_id] = widget_model;
+        var widget_module = msg.content.data.model_module;
+
+        if (widget_module) {
+            // Load the module containing the widget model
+            require([widget_module], function(mod) {
+                if (mod[widget_type_name]) {
+                    instantiate_model(mod[widget_type_name]);
+                } else {
+                    console.log("Error creating widget model: " + widget_type_name
+                            + " not found in " + widget_module);
+                }
+            }, function(err) { console.log(err); });
+        } else {
+            // No module specified, load from the global models registry
+            instantiate_model(WidgetManager._model_types[widget_type_name]);
+        }
     };
 
     // Backwards compatability.
diff --git a/IPython/html/widgets/widget.py b/IPython/html/widgets/widget.py
index 86e85aa82..f1571eab4 100644
--- a/IPython/html/widgets/widget.py
+++ b/IPython/html/widgets/widget.py
@@ -98,6 +98,8 @@ class Widget(LoggingConfigurable):
     #-------------------------------------------------------------------------
     # Traits
     #-------------------------------------------------------------------------
+    _model_module = Unicode(None, allow_none=True, help="""A requirejs module name
+        in which to find _model_name. If empty, look in the global registry.""")
     _model_name = Unicode('WidgetModel', help="""Name of the backbone model 
         registered in the front-end to create and sync this widget with.""")
     _view_module = Unicode(help="""A requirejs module in which to find _view_name.
@@ -142,7 +144,9 @@ class Widget(LoggingConfigurable):
     def open(self):
         """Open a comm to the frontend if one isn't already open."""
         if self.comm is None:
-            args = dict(target_name='ipython.widget', data={ 'model_name': self._model_name })
+            args = dict(target_name='ipython.widget',
+                        data={'model_name': self._model_name,
+                              'model_module': self._model_module})
             if self._model_id is not None:
                 args['comm_id'] = self._model_id
             self.comm = Comm(**args)