diff --git a/src/body/Body.js b/src/body/Body.js
index a32ec7b..9f1f7c6 100644
--- a/src/body/Body.js
+++ b/src/body/Body.js
@@ -22,6 +22,7 @@ var Body = {};
         var defaults = {
             id: Body.nextId(),
             type: 'body',
+            label: null,
             angle: 0,
             position: { x: 0, y: 0 },
             force: { x: 0, y: 0 },
diff --git a/src/body/Composite.js b/src/body/Composite.js
index 9cfae5e..b2a8bb7 100644
--- a/src/body/Composite.js
+++ b/src/body/Composite.js
@@ -27,7 +27,8 @@ var Composite = {};
             isModified: false,
             bodies: [], 
             constraints: [], 
-            composites: [] 
+            composites: [],
+            label: null
         }, options);
     };
 
diff --git a/src/body/World.js b/src/body/World.js
index 6740155..872a181 100644
--- a/src/body/World.js
+++ b/src/body/World.js
@@ -20,6 +20,7 @@ var World = {};
         var composite = Composite.create();
 
         var defaults = {
+            label: 'World',
             gravity: { x: 0, y: 1 },
             bounds: { 
                 min: { x: 0, y: 0 }, 
diff --git a/src/constraint/Constraint.js b/src/constraint/Constraint.js
index ce1324b..d76f2b1 100644
--- a/src/constraint/Constraint.js
+++ b/src/constraint/Constraint.js
@@ -54,6 +54,7 @@ var Constraint = {};
 
         // option defaults
         constraint.id = constraint.id || Constraint.nextId();
+        constraint.label = constraint.label;
         constraint.type = 'constraint';
         constraint.stiffness = constraint.stiffness || 1;
         constraint.angularStiffness = constraint.angularStiffness || 0;
diff --git a/src/constraint/MouseConstraint.js b/src/constraint/MouseConstraint.js
index a3d6a00..0c65e6c 100644
--- a/src/constraint/MouseConstraint.js
+++ b/src/constraint/MouseConstraint.js
@@ -20,6 +20,7 @@ var MouseConstraint = {};
         var mouse = engine.input.mouse;
 
         var constraint = Constraint.create({ 
+            label: 'Mouse Constraint',
             pointA: mouse.position,
             pointB: { x: 0, y: 0 },
             length: 0.01,