diff --git a/common/changes/office-ui-fabric-react/jspurlin-ContextualMenuFixSplitButtonSubmenuTarget_2018-03-14-22-41.json b/common/changes/office-ui-fabric-react/jspurlin-ContextualMenuFixSplitButtonSubmenuTarget_2018-03-14-22-41.json
new file mode 100644
index 0000000000000..64c43c559bc62
--- /dev/null
+++ b/common/changes/office-ui-fabric-react/jspurlin-ContextualMenuFixSplitButtonSubmenuTarget_2018-03-14-22-41.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "office-ui-fabric-react",
+      "comment": "ContextualMenu: SplitButtons in ContextualMenus are incorrectly using the menuLauncher portion of the splitButton for the tagrate when the  menuLauncher portion is  activated. This can lead to weird overhangs of the parent menu even if  directionalHintFixed is not true (e.g. it will overlap the primary portion of the  splitButton and potentially other items in the parent menu)",
+      "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 4f531f196a895..9f9a3e484bd3c 100644
--- a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
+++ b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
@@ -660,7 +660,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
   private _renderSplitIconButton(item: IContextualMenuItem, classNames: IMenuItemClassNames, index: number) {
     const { contextualMenuItemAs: ChildrenRenderer = ContextualMenuItem } = this.props;
     const itemProps = {
-      onClick: this._onItemClick.bind(this, item),
+      onClick: this._onSplitItemClick.bind(this, item),
       disabled: this._isItemDisabled(item),
       className: classNames.splitMenu,
       subMenuProps: item.subMenuProps,
@@ -810,7 +810,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
    * As part of updating focus, This function will also update
    * the expand/collapse state accordingly.
    */
-  private _updateFocusOnMouseEvent(item: any, ev: React.MouseEvent<HTMLElement>) {
+  private _updateFocusOnMouseEvent(item: IContextualMenuItem, ev: React.MouseEvent<HTMLElement>) {
     const targetElement = ev.currentTarget as HTMLElement;
     const { subMenuHoverDelay: timeoutDuration = this._navigationIdleDelay } = this.props;
 
@@ -833,8 +833,10 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
     if (hasSubmenu(item)) {
       this._enterTimerId = this._async.setTimeout(() => {
         targetElement.focus();
-        this._onItemSubMenuExpand(item, targetElement);
-      }, timeoutDuration);
+        const splitButtonContainer = this._splitButtonContainers.get(item.key);
+        this._onItemSubMenuExpand(item,
+          ((item.split && splitButtonContainer) ? splitButtonContainer : targetElement) as HTMLElement);
+      }, this._navigationIdleDelay);
     } else {
       this._enterTimerId = this._async.setTimeout(() => {
         this._onSubMenuDismiss(ev);
@@ -850,6 +852,17 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
   }
 
   private _onItemClick(item: IContextualMenuItem, ev: React.MouseEvent<HTMLElement>) {
+    this._onItemClickBase(item, ev, ev.currentTarget as HTMLElement);
+  }
+
+  private _onSplitItemClick(item: IContextualMenuItem, ev: React.MouseEvent<HTMLElement>) {
+    const splitButtonContainer = this._splitButtonContainers.get(item.key);
+    // get the whole splitButton container to base the menu off of
+    this._onItemClickBase(item, ev,
+      (splitButtonContainer ? splitButtonContainer : ev.currentTarget) as HTMLElement);
+  }
+
+  private _onItemClickBase(item: IContextualMenuItem, ev: React.MouseEvent<HTMLElement>, target: HTMLElement) {
     const items = getSubmenuItems(item);
 
     if (!hasSubmenu(item) && (!items || !items.length)) { // This is an item without a menu. Click it.
@@ -858,7 +871,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
       if (item.key === this.state.expandedMenuItemKey) { // This has an expanded sub menu. collapse it.
         this._onSubMenuDismiss(ev);
       } else { // This has a collapsed sub menu. Expand it.
-        this._onItemSubMenuExpand(item, ev.currentTarget as HTMLElement);
+        this._onItemSubMenuExpand(item, target);
       }
     }
 
@@ -901,11 +914,8 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
         this._onSubMenuDismiss();
       }
 
-      // focus the container so when we close the menu, we focus on the split button container.
-      const el = this._splitButtonContainers.get(item.key);
-      if (el) {
-        el.focus();
-      }
+      // Focus the target to ensure when we close it, we're focusing on the correct element.
+      target.focus();
       this.setState({
         expandedMenuItemKey: item.key,
         submenuTarget: target
diff --git a/packages/office-ui-fabric-react/src/components/ContextualMenu/examples/ContextualMenu.Checkmarks.Example.tsx b/packages/office-ui-fabric-react/src/components/ContextualMenu/examples/ContextualMenu.Checkmarks.Example.tsx
index cda9329015042..1eed388377c90 100644
--- a/packages/office-ui-fabric-react/src/components/ContextualMenu/examples/ContextualMenu.Checkmarks.Example.tsx
+++ b/packages/office-ui-fabric-react/src/components/ContextualMenu/examples/ContextualMenu.Checkmarks.Example.tsx
@@ -1,5 +1,5 @@
 import * as React from 'react';
-import { IContextualMenuItem, ContextualMenuItemType } from 'office-ui-fabric-react/lib/ContextualMenu';
+import { IContextualMenuItem, ContextualMenuItemType, DirectionalHint } from 'office-ui-fabric-react/lib/ContextualMenu';
 import { DefaultButton } from 'office-ui-fabric-react/lib/Button';
 import './ContextualMenuExample.scss';
 
@@ -7,7 +7,7 @@ export interface IContextualMenuMultiselectExampleState {
   selection?: { [key: string]: boolean };
 }
 
-const keys: string[] = ['newItem', 'share', 'mobile', 'enablePrint', 'enableMusic', 'newSub', 'emailMessage', 'calendarEvent', 'disabledNewSub', 'disabledEmailMessage', 'disabledCalendarEvent'];
+const keys: string[] = ['newItem', 'share', 'mobile', 'enablePrint', 'enableMusic', 'newSub', 'emailMessage', 'calendarEvent', 'disabledNewSub', 'disabledEmailMessage', 'disabledCalendarEvent', 'splitButtonSubMenuLeftDirection', 'emailMessageLeft', 'calendarEventLeft'];
 
 export class ContextualMenuCheckmarksExample extends React.Component<{}, IContextualMenuMultiselectExampleState> {
 
@@ -110,14 +110,14 @@ export class ContextualMenuCheckmarksExample extends React.Component<{}, IContex
                   subMenuProps: {
                     items: [
                       {
-                        key: keys[6],
+                        key: keys[9],
                         name: 'Email message',
                         canCheck: true,
                         isChecked: selection![keys[9]],
                         onClick: this._onToggleSelect
                       },
                       {
-                        key: keys[7],
+                        key: keys[10],
                         name: 'Calendar event',
                         canCheck: true,
                         isChecked: selection![keys[10]],
@@ -132,6 +132,36 @@ export class ContextualMenuCheckmarksExample extends React.Component<{}, IContex
                   onClick: this._onToggleSelect,
                   disabled: true
                 },
+                {
+                  key: keys[11],
+                  iconProps: {
+                    iconName: 'MusicInCollectionFill'
+                  },
+                  subMenuProps: {
+                    directionalHint: DirectionalHint.leftCenter,
+                    items: [
+                      {
+                        key: keys[12],
+                        name: 'Email message',
+                        canCheck: true,
+                        isChecked: selection![keys[12]],
+                        onClick: this._onToggleSelect
+                      },
+                      {
+                        key: keys[13],
+                        name: 'Calendar event',
+                        canCheck: true,
+                        isChecked: selection![keys[13]],
+                        onClick: this._onToggleSelect
+                      }
+                    ],
+                  },
+                  name: 'Split Button Left Menu',
+                  canCheck: true,
+                  isChecked: selection![keys[11]],
+                  split: true,
+                  onClick: this._onToggleSelect,
+                },
               ]
           }
         }