diff --git a/common/changes/office-ui-fabric-react/jspurlin-AllowSubMenusToCollapseOnPrimarySplitButton_2018-04-11-14-51.json b/common/changes/office-ui-fabric-react/jspurlin-AllowSubMenusToCollapseOnPrimarySplitButton_2018-04-11-14-51.json
new file mode 100644
index 0000000000000..371fc0097714c
--- /dev/null
+++ b/common/changes/office-ui-fabric-react/jspurlin-AllowSubMenusToCollapseOnPrimarySplitButton_2018-04-11-14-51.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "office-ui-fabric-react",
+      "comment": "SplitButton: Allow the primary portion of a splitButton (when it a menu) to collapse a submenu",
+      "type": "patch"
+    }
+  ],
+  "packageName": "office-ui-fabric-react",
+  "email": "jspurlin@microsoft.com"
+}
\ No newline at end of file
diff --git a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
index 5a9d3293b8ada..3eb59b337e11f 100644
--- a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
+++ b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
@@ -604,6 +604,9 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
         aria-checked={ item.isChecked || item.checked }
         aria-posinset={ focusableElementIndex + 1 }
         aria-setsize={ totalItemCount }
+        onMouseEnter={ this._onItemMouseEnter.bind(this, { ...item, subMenuProps: null, items: null }) }
+        onMouseLeave={ this._onMouseItemLeave.bind(this, { ...item, subMenuProps: null, items: null }) }
+        onMouseMove={ this._onItemMouseMove.bind(this, { ...item, subMenuProps: null, items: null }) }
         onKeyDown={ this._onSplitContainerItemKeyDown.bind(this, item) }
         onClick={ this._executeItemClick.bind(this, item) }
         tabIndex={ 0 }
@@ -831,6 +834,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
     // Delay updating expanding/dismissing the submenu
     // and only set focus if we have not already done so
     if (hasSubmenu(item)) {
+      ev.stopPropagation();
       this._enterTimerId = this._async.setTimeout(() => {
         targetElement.focus();
         const splitButtonContainer = this._splitButtonContainers.get(item.key);