--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -79,16 +79,20 @@ function pktUIGetter(prop) {
     },
     configurable: true,
     enumerable: true
   };
 }
 Object.defineProperty(window, "pktUI", pktUIGetter("pktUI"));
 Object.defineProperty(window, "pktUIMessaging", pktUIGetter("pktUIMessaging"));
 
+XPCOMUtils.defineLazyGetter(this, "gBrowserBundle", function() {
+  return Services.strings.createBundle('chrome://browser/locale/browser.properties');
+});
+
 const nsIWebNavigation = Ci.nsIWebNavigation;
 
 var gLastBrowserCharset = null;
 var gProxyFavIcon = null;
 var gLastValidURLStr = "";
 var gInPrintPreviewMode = false;
 var gContextMenu = null; // nsContextMenu instance
 var gMultiProcessBrowser =
@@ -4029,16 +4033,51 @@ function openNewUserContextTab(event)
  */
 function updateUserContextUIVisibility()
 {
   let userContextEnabled = Services.prefs.getBoolPref("privacy.userContext.enabled");
   document.getElementById("menu_newUserContext").hidden = !userContextEnabled;
 }
 
 /**
+ * Updates the User Context UI indicators if the browser is in a non-default context
+ */
+function updateUserContextUIIndicator(browser)
+{
+  let hbox = document.getElementById("userContext-icons");
+
+  if (!browser.hasAttribute("usercontextid")) {
+    hbox.removeAttribute("usercontextid");
+    return;
+  }
+
+  let label = document.getElementById("userContext-label");
+  let userContextId = browser.getAttribute("usercontextid");
+  hbox.setAttribute("usercontextid", userContextId);
+  switch (userContextId) {
+    case "1":
+      label.value = gBrowserBundle.GetStringFromName("usercontext.personal.label");
+      break;
+    case "2":
+      label.value = gBrowserBundle.GetStringFromName("usercontext.work.label");
+      break;
+    case "3":
+      label.value = gBrowserBundle.GetStringFromName("usercontext.banking.label");
+      break;
+    case "4":
+      label.value = gBrowserBundle.GetStringFromName("usercontext.shopping.label");
+      break;
+    // Display the context IDs for values outside the pre-defined range.
+    // Used for debugging, no localization necessary.
+    default:
+      label.value = "Context " + userContextId;
+  }
+}
+
+/**
  * Makes the Character Encoding menu enabled or disabled as appropriate.
  * To be called when the View menu or the app menu is opened.
  */
 function updateCharacterEncodingMenuState()
 {
   let charsetMenu = document.getElementById("charsetMenu");
   // gBrowser is null on Mac when the menubar shows in the context of
   // non-browser windows. The above elements may be null depending on

--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -763,16 +763,20 @@
                        hidden="true"
                        tooltiptext="&pageReportIcon.tooltip;"
                        onclick="gPopupBlockerObserver.onReportButtonClick(event);"/>
                 <image id="reader-mode-button"
                        class="urlbar-icon"
                        hidden="true"
                        onclick="ReaderParent.buttonClick(event);"/>
               </hbox>
+              <hbox id="userContext-icons">
+                <label id="userContext-label"/>
+                <image id="userContext-indicator"/>
+              </hbox>
               <toolbarbutton id="urlbar-go-button"
                              class="chromeclass-toolbar-additional"
                              onclick="gURLBar.handleCommand(event);"
                              tooltiptext="&goEndCap.tooltip;"/>
               <toolbarbutton id="urlbar-reload-button"
                              class="chromeclass-toolbar-additional"
                              command="Browser:ReloadOrDuplicate"
                              onclick="checkForMiddleClick(this, event);"

--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -1231,16 +1231,18 @@
                 // some element has been focused and respect that.
                 document.activeElement.blur();
               }
 
               if (!gMultiProcessBrowser)
                 this._adjustFocusAfterTabSwitch(this.mCurrentTab);
             }
 
+            updateUserContextUIIndicator(gBrowser.selectedBrowser);
+
             this.tabContainer._setPositionalAttributes();
 
             if (!gMultiProcessBrowser) {
               let event = new CustomEvent("TabSwitchDone", {
                 bubbles: true,
                 cancelable: true
               });
               this.dispatchEvent(event);

--- a/browser/locales/en-US/chrome/browser/browser.properties
+++ b/browser/locales/en-US/chrome/browser/browser.properties
@@ -771,12 +771,30 @@ e10s.postActivationInfobar.message = You
 e10s.postActivationInfobar.learnMore.label = Learn More
 e10s.postActivationInfobar.learnMore.accesskey = L
 e10s.accessibilityNotice.mainMessage = Multi-process does not yet support accessibility features. Multi-process will be disabled if you restart %S. Would you like to restart?
 e10s.accessibilityNotice.disableAndRestart.label = Disable and Restart
 e10s.accessibilityNotice.disableAndRestart.accesskey = R
 e10s.accessibilityNotice.dontDisable.label = Don't Disable
 e10s.accessibilityNotice.dontDisable.accesskey = D
 
+# LOCALIZATION NOTE (usercontext.personal.label,
+#                    usercontext.work.label,
+#                    usercontext.shopping.label,
+#                    usercontext.banking.label):
+# These strings specify the four default contexts included in support of the
+# Contextual Identity / Containers project. Each context is meant to represent
+# the context that the user is in when interacting with the site. Different
+# contexts will store cookies and other information from those sites in
+# different, isolated locations. You can enable the feature by typing
+# about:config in the URL bar and changing privacy.userContext.enabled to true.
+# Once enabled, you can open a new tab in a specific context by clicking
+# File > New Container Tab > (1 of 4 contexts). Once opened, you will see these
+# strings on the right-hand side of the URL bar.
+usercontext.personal.label = Personal
+usercontext.work.label = Work
+usercontext.shopping.label = Shopping
+usercontext.banking.label = Banking
+
 muteTab.label = Mute Tab
 muteTab.accesskey = M
 unmuteTab.label = Unmute Tab
 unmuteTab.accesskey = M

--- a/browser/themes/shared/usercontext/usercontext.inc.css
+++ b/browser/themes/shared/usercontext/usercontext.inc.css
@@ -10,8 +10,60 @@
 
 #menu_newUserContextTabBanking {
   list-style-image: url("chrome://browser/skin/usercontext/banking.svg");
 }
 
 #menu_newUserContextTabShopping {
   list-style-image: url("chrome://browser/skin/usercontext/shopping.svg");
 }
+
+/* URL Bar Decoration */
+
+#userContext-indicator {
+  height: 16px;
+  width: 16px;
+}
+
+#userContext-label {
+  margin-inline-end: 3px;
+  color: #909090;
+}
+
+#userContext-icons:not([usercontextid]) {
+  display: none;
+}
+
+#userContext-icons {
+  -moz-box-align: center;
+}
+
+/* Personal User Context */
+#userContext-icons[usercontextid="1"] > #userContext-label {
+  color: #00a7e0;
+}
+#userContext-icons[usercontextid="1"] > #userContext-indicator {
+  list-style-image: url("chrome://browser/skin/usercontext/personal.svg");
+}
+
+/* Work User Context */
+#userContext-icons[usercontextid="2"] > #userContext-label {
+  color: #f89c24;
+}
+#userContext-icons[usercontextid="2"] > #userContext-indicator {
+  list-style-image: url("chrome://browser/skin/usercontext/work.svg");
+}
+
+/* Banking User Context */
+#userContext-icons[usercontextid="3"] > #userContext-label {
+  color: #7dc14c;
+}
+#userContext-icons[usercontextid="3"] > #userContext-indicator {
+  list-style-image: url("chrome://browser/skin/usercontext/banking.svg");
+}
+
+/* Shopping User Context */
+#userContext-icons[usercontextid="4"] > #userContext-label {
+  color: #ee5195;
+}
+#userContext-icons[usercontextid="4"] > #userContext-indicator {
+  list-style-image: url("chrome://browser/skin/usercontext/shopping.svg");
+}