diff --git a/change/office-ui-fabric-react-2020-09-10-13-31-38-user-cimoli-again.json b/change/office-ui-fabric-react-2020-09-10-13-31-38-user-cimoli-again.json
new file mode 100644
index 00000000000000..5ecea2cece485f
--- /dev/null
+++ b/change/office-ui-fabric-react-2020-09-10-13-31-38-user-cimoli-again.json
@@ -0,0 +1,8 @@
+{
+  "type": "patch",
+  "comment": "change roles for nav items to tab to use aria-selected",
+  "packageName": "office-ui-fabric-react",
+  "email": "cimoli@microsoft.com",
+  "dependentChangeType": "patch",
+  "date": "2020-09-10T20:31:37.999Z"
+}
diff --git a/packages/office-ui-fabric-react/src/components/Nav/Nav.base.tsx b/packages/office-ui-fabric-react/src/components/Nav/Nav.base.tsx
index 40bfdb5ba59e5f..c0d3a0b9b620b7 100644
--- a/packages/office-ui-fabric-react/src/components/Nav/Nav.base.tsx
+++ b/packages/office-ui-fabric-react/src/components/Nav/Nav.base.tsx
@@ -187,9 +187,11 @@ export class NavBase extends React.Component<INavProps, INavState> implements IN
   private _renderLink(link: INavLink, linkIndex: number, nestingLevel: number): React.ReactElement<{}> {
     const { styles, groups, theme } = this.props;
     const classNames = getClassNames(styles!, { theme: theme!, groups });
-
+    const isSelected = this._isLinkSelected(link);
     return (
-      <li key={link.key || linkIndex} role="listitem" className={classNames.navItem}>
+      // Known issue: Aria-selected and aria-checked are not output correctly for trees
+      // https://github.com/FreedomScientific/VFO-standards-support/issues/432
+      <li key={link.key || linkIndex} role="treeitem" className={classNames.navItem} aria-selected={isSelected}>
         {this._renderCompositeLink(link, linkIndex, nestingLevel)}
         {link.isExpanded ? this._renderLinks(link.links, ++nestingLevel) : null}
       </li>
@@ -208,7 +210,7 @@ export class NavBase extends React.Component<INavProps, INavState> implements IN
     const classNames = getClassNames(styles!, { theme: theme!, groups });
 
     return (
-      <ul role="list" className={classNames.navItems}>
+      <ul role="tree" className={classNames.navItems}>
         {linkElements}
       </ul>
     );
diff --git a/packages/office-ui-fabric-react/src/components/Nav/__snapshots__/Nav.test.tsx.snap b/packages/office-ui-fabric-react/src/components/Nav/__snapshots__/Nav.test.tsx.snap
index 73767dcbba0f9c..5c36d6b799aa56 100644
--- a/packages/office-ui-fabric-react/src/components/Nav/__snapshots__/Nav.test.tsx.snap
+++ b/packages/office-ui-fabric-react/src/components/Nav/__snapshots__/Nav.test.tsx.snap
@@ -139,9 +139,10 @@ exports[`Nav render Nav with overrides correctly 1`] = `
                 padding-right: 0px;
                 padding-top: 0px;
               }
-          role="list"
+          role="tree"
         >
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -150,7 +151,7 @@ exports[`Nav render Nav with overrides correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -299,6 +300,7 @@ exports[`Nav render Nav with overrides correctly 1`] = `
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -307,7 +309,7 @@ exports[`Nav render Nav with overrides correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -518,9 +520,10 @@ exports[`Nav renders Nav correctly 1`] = `
                 padding-right: 0px;
                 padding-top: 0px;
               }
-          role="list"
+          role="tree"
         >
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -529,7 +532,7 @@ exports[`Nav renders Nav correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
diff --git a/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Basic.Example.tsx.shot b/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Basic.Example.tsx.shot
index ad289e6cbe6907..d21a67c352506f 100644
--- a/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Basic.Example.tsx.shot
+++ b/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Basic.Example.tsx.shot
@@ -61,9 +61,10 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                 padding-right: 0px;
                 padding-top: 0px;
               }
-          role="list"
+          role="tree"
         >
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -72,7 +73,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -308,9 +309,10 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                     padding-right: 0px;
                     padding-top: 0px;
                   }
-              role="list"
+              role="tree"
             >
               <li
+                aria-selected={false}
                 className=
                     ms-Nav-navItem
                     {
@@ -319,7 +321,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                       padding-right: 0px;
                       padding-top: 0px;
                     }
-                role="listitem"
+                role="treeitem"
               >
                 <div
                   className=
@@ -462,6 +464,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                 </div>
               </li>
               <li
+                aria-selected={false}
                 className=
                     ms-Nav-navItem
                     {
@@ -470,7 +473,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                       padding-right: 0px;
                       padding-top: 0px;
                     }
-                role="listitem"
+                role="treeitem"
               >
                 <div
                   className=
@@ -606,6 +609,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
             </ul>
           </li>
           <li
+            aria-selected={true}
             className=
                 ms-Nav-navItem
                 {
@@ -614,7 +618,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -770,6 +774,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -778,7 +783,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -921,6 +926,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -929,7 +935,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -1063,6 +1069,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -1071,7 +1078,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -1214,6 +1221,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -1222,7 +1230,7 @@ exports[`Component Examples renders Nav.Basic.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
diff --git a/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.CustomGroupHeaders.Example.tsx.shot b/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.CustomGroupHeaders.Example.tsx.shot
index 64538ded84f701..dd563c844d13d7 100644
--- a/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.CustomGroupHeaders.Example.tsx.shot
+++ b/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.CustomGroupHeaders.Example.tsx.shot
@@ -60,9 +60,10 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
                 padding-right: 0px;
                 padding-top: 0px;
               }
-          role="list"
+          role="tree"
         >
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -71,7 +72,7 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -214,6 +215,7 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -222,7 +224,7 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -399,9 +401,10 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
                 padding-right: 0px;
                 padding-top: 0px;
               }
-          role="list"
+          role="tree"
         >
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -410,7 +413,7 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -553,6 +556,7 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -561,7 +565,7 @@ exports[`Component Examples renders Nav.CustomGroupHeaders.Example.tsx correctly
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
diff --git a/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Nested.Example.tsx.shot b/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Nested.Example.tsx.shot
index 6c1c996494ccc5..57cda14fd73d92 100644
--- a/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Nested.Example.tsx.shot
+++ b/packages/office-ui-fabric-react/src/components/__snapshots__/Nav.Nested.Example.tsx.shot
@@ -57,9 +57,10 @@ exports[`Component Examples renders Nav.Nested.Example.tsx correctly 1`] = `
                 padding-right: 0px;
                 padding-top: 0px;
               }
-          role="list"
+          role="tree"
         >
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -68,7 +69,7 @@ exports[`Component Examples renders Nav.Nested.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=
@@ -292,6 +293,7 @@ exports[`Component Examples renders Nav.Nested.Example.tsx correctly 1`] = `
             </div>
           </li>
           <li
+            aria-selected={false}
             className=
                 ms-Nav-navItem
                 {
@@ -300,7 +302,7 @@ exports[`Component Examples renders Nav.Nested.Example.tsx correctly 1`] = `
                   padding-right: 0px;
                   padding-top: 0px;
                 }
-            role="listitem"
+            role="treeitem"
           >
             <div
               className=