diff --git a/src/item/Item.js b/src/item/Item.js
index fbe2aa66..4bbcf118 100644
--- a/src/item/Item.js
+++ b/src/item/Item.js
@@ -411,7 +411,7 @@ Item = Base.extend({
 	 * @return {@true if it is inside the specified item}
 	 */
 	isDescendant: function(item) {
-		var parent = this;
+		var parent = this.parent;
 		while(parent) {
 			if (parent == item)
 				return true;
@@ -436,7 +436,7 @@ Item = Base.extend({
 	 * @return {@true if the item is an ancestor of the specified item}
 	 */
 	isAncestor: function(item) {
-		var parent = item;
+		var parent = item.parent;
 		while(parent) {
 			if (parent == this)
 				return true;
@@ -451,7 +451,21 @@ Item = Base.extend({
 	 * @param item
 	 * @return {@true if the items are grouped together}
 	 */
-	// TODO: isGroupedWith
+	isGroupedWith: function(item) {
+		var parent = this.parent;
+		while(parent) {
+			// Find group parents. Check for parent.parent, since don't want
+			// top level layers, because they also inherit from Group
+			console.log(parent.parent);
+			if(parent.parent
+				&& (parent instanceof Group || parent instanceof CompoundPath)
+				&& item.isDescendant(parent))
+					return true;
+			// Keep walking up otherwise
+			parent = parent.parent
+		}
+		return false;
+	},
 	
 	getBounds: function() {
 		// TODO: Implement for items other than paths
diff --git a/test/tests/item.js b/test/tests/item.js
index 7262a714..1c141040 100644
--- a/test/tests/item.js
+++ b/test/tests/item.js
@@ -89,6 +89,33 @@ test('isDescendant(item) / isAncestor(item)', function() {
 
 	equals(path.isAncestor(doc.activeLayer), false);
 	equals(doc.activeLayer.isAncestor(path), true);
+	
+	// an item can't be its own descendant:
+	equals(doc.activeLayer.isDescendant(doc.activeLayer), false);
+
+	// an item can't be its own ancestor:
+	equals(doc.activeLayer.isAncestor(doc.activeLayer), false);
+});
+
+test('isGroupedWith', function() {
+	var doc = new Doc();
+	var path = new Path();
+	var secondPath = new Path();
+	var group = new Group([path]);
+	var secondGroup = new Group([secondPath]);
+	
+	equals(path.isGroupedWith(secondPath), false);
+	secondGroup.appendTop(path);
+	equals(path.isGroupedWith(secondPath), true);
+	equals(path.isGroupedWith(group), false);
+	equals(path.isDescendant(secondGroup), true);
+	equals(secondGroup.isDescendant(path), false);
+	equals(secondGroup.isDescendant(secondGroup), false);
+	equals(path.isGroupedWith(secondGroup), false);
+	Paper.document.activeLayer.appendTop(path);
+	equals(path.isGroupedWith(secondPath), false);
+	Paper.document.activeLayer.appendTop(secondPath);
+	equals(path.isGroupedWith(secondPath), false);
 });
 
 test('getPreviousSibling() / getNextSibling()', function() {