diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 511178b5e7de..fc58acb41e35 100755
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -8,6 +8,7 @@ var Cu = Components.utils;
 var Cc = Components.classes;
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/ContextualIdentityService.jsm");
 Cu.import("resource://gre/modules/NotificationDB.jsm");
 Cu.import("resource:///modules/RecentWindow.jsm");
 
@@ -56,8 +57,6 @@ XPCOMUtils.defineLazyServiceGetter(this, "WindowsUIUtils",
                                    "@mozilla.org/windows-ui-utils;1", "nsIWindowsUIUtils");
 XPCOMUtils.defineLazyModuleGetter(this, "LightweightThemeManager",
                                   "resource://gre/modules/LightweightThemeManager.jsm");
-XPCOMUtils.defineLazyModuleGetter(this, "ContextualIdentityService",
-                                  "resource://gre/modules/ContextualIdentityService.jsm");
 XPCOMUtils.defineLazyServiceGetter(this, "gAboutNewTabService",
                                    "@mozilla.org/browser/aboutnewtab-service;1",
                                    "nsIAboutNewTabService");
diff --git a/browser/base/content/nsContextMenu.js b/browser/base/content/nsContextMenu.js
index 124847b00beb..263b13737dcb 100644
--- a/browser/base/content/nsContextMenu.js
+++ b/browser/base/content/nsContextMenu.js
@@ -4,6 +4,7 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+Components.utils.import("resource://gre/modules/ContextualIdentityService.jsm");
 Components.utils.import("resource://gre/modules/PrivateBrowsingUtils.jsm");
 Components.utils.import("resource://gre/modules/InlineSpellChecker.jsm");
 Components.utils.import("resource://gre/modules/LoginManagerContextMenu.jsm");
@@ -11,8 +12,6 @@ Components.utils.import("resource://gre/modules/BrowserUtils.jsm");
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 Components.utils.import("resource://gre/modules/Services.jsm");
 
-XPCOMUtils.defineLazyModuleGetter(this, "ContextualIdentityService",
-                                  "resource://gre/modules/ContextualIdentityService.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "LoginHelper",
   "resource://gre/modules/LoginHelper.jsm");
diff --git a/browser/base/content/utilityOverlay.js b/browser/base/content/utilityOverlay.js
index dbddd6de62a3..458a3563ed3b 100644
--- a/browser/base/content/utilityOverlay.js
+++ b/browser/base/content/utilityOverlay.js
@@ -5,6 +5,7 @@
 
 // Services = object with smart getters for common XPCOM services
 Components.utils.import("resource://gre/modules/AppConstants.jsm");
+Components.utils.import("resource://gre/modules/ContextualIdentityService.jsm");
 Components.utils.import("resource://gre/modules/Services.jsm");
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 Components.utils.import("resource://gre/modules/PrivateBrowsingUtils.jsm");
@@ -13,9 +14,6 @@ Components.utils.import("resource:///modules/RecentWindow.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ShellService",
                                   "resource:///modules/ShellService.jsm");
 
-XPCOMUtils.defineLazyModuleGetter(this, "ContextualIdentityService",
-                                  "resource://gre/modules/ContextualIdentityService.jsm");
-
 XPCOMUtils.defineLazyServiceGetter(this, "aboutNewTabService",
                                    "@mozilla.org/browser/aboutnewtab-service;1",
                                    "nsIAboutNewTabService");
diff --git a/toolkit/components/contextualidentity/ContextualIdentityService.jsm b/toolkit/components/contextualidentity/ContextualIdentityService.jsm
index 31a4aabea8c5..59b8c5acd414 100644
--- a/toolkit/components/contextualidentity/ContextualIdentityService.jsm
+++ b/toolkit/components/contextualidentity/ContextualIdentityService.jsm
@@ -7,16 +7,34 @@ this.EXPORTED_SYMBOLS = ["ContextualIdentityService"];
 const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
-Cu.import("resource://gre/modules/Services.jsm")
+Cu.import("resource://gre/modules/Services.jsm");
 
-const DEFAULT_TAB_COLOR = "#909090"
+const DEFAULT_TAB_COLOR = "#909090";
+const SAVE_DELAY_MS = 1500;
 
 XPCOMUtils.defineLazyGetter(this, "gBrowserBundle", function() {
   return Services.strings.createBundle("chrome://browser/locale/browser.properties");
 });
 
+XPCOMUtils.defineLazyGetter(this, "gTextDecoder", function () {
+  return new TextDecoder();
+});
+
+XPCOMUtils.defineLazyGetter(this, "gTextEncoder", function () {
+  return new TextEncoder();
+});
+
+XPCOMUtils.defineLazyModuleGetter(this, "AsyncShutdown",
+                                  "resource://gre/modules/AsyncShutdown.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "OS",
+                                  "resource://gre/modules/osfile.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "DeferredTask",
+                                  "resource://gre/modules/DeferredTask.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
+                                  "resource://gre/modules/FileUtils.jsm");
+
 this.ContextualIdentityService = {
-  _identities: [
+  _defaultIdentities: [
     { userContextId: 1,
       public: true,
       icon: "chrome://browser/skin/usercontext/personal.svg",
@@ -62,15 +80,107 @@ this.ContextualIdentityService = {
       alreadyOpened: false },
   ],
 
+  _identities: null,
+
+  _path: null,
+  _dataReady: false,
+
+  _saver: null,
+
+  init() {
+    this._path = OS.Path.join(OS.Constants.Path.profileDir, "containers.json");
+
+    this._saver = new DeferredTask(() => this.save(), SAVE_DELAY_MS);
+    AsyncShutdown.profileBeforeChange.addBlocker("ContextualIdentityService: writing data",
+                                                 () => this._saver.finalize());
+
+    this.load();
+  },
+
+  load() {
+    OS.File.read(this._path).then(bytes => {
+      // If synchronous loading happened in the meantime, exit now.
+      if (this._dataReady) {
+        return;
+      }
+
+      try {
+        this._identities = JSON.parse(gTextDecoder.decode(bytes));
+        this._dataReady = true;
+      } catch(error) {
+        this.loadError(error);
+      }
+    }, (error) => {
+      this.loadError(error);
+    });
+  },
+
+  loadError(error) {
+    if (!(error instanceof OS.File.Error && error.becauseNoSuchFile) &&
+        !(error instanceof Components.Exception &&
+          error.result == Cr.NS_ERROR_FILE_NOT_FOUND)) {
+      // Let's report the error.
+      Cu.reportError(error);
+    }
+
+    // If synchronous loading happened in the meantime, exit now.
+    if (this._dataReady) {
+      return;
+    }
+
+    this._identities = this._defaultIdentities;
+    this._dataReady = true;
+
+    this.saveSoon();
+  },
+
+  saveSoon() {
+    this._saver.arm();
+  },
+
+  save() {
+   let bytes = gTextEncoder.encode(JSON.stringify(this._identities));
+   return OS.File.writeAtomic(this._path, bytes,
+                              { tmpPath: this._path + ".tmp" });
+  },
+
+  ensureDataReady() {
+    if (this._dataReady) {
+      return;
+    }
+
+    try {
+      // This reads the file and automatically detects the UTF-8 encoding.
+      let inputStream = Cc["@mozilla.org/network/file-input-stream;1"]
+                          .createInstance(Ci.nsIFileInputStream);
+      inputStream.init(new FileUtils.File(this._path),
+                       FileUtils.MODE_RDONLY, FileUtils.PERMS_FILE, 0);
+      try {
+        let json = Cc["@mozilla.org/dom/json;1"].createInstance(Ci.nsIJSON);
+        this._identities = json.decodeFromStream(inputStream,
+                                                 inputStream.available());
+        this._dataReady = true;
+      } finally {
+        inputStream.close();
+      }
+    } catch (error) {
+      this.loadError(error);
+      return;
+    }
+  },
+
   getIdentities() {
+    this.ensureDataReady();
     return this._identities.filter(info => info.public);
   },
 
   getPrivateIdentity(label) {
+    this.ensureDataReady();
     return this._identities.find(info => !info.public && info.label == label);
   },
 
   getIdentityFromId(userContextId) {
+    this.ensureDataReady();
     return this._identities.find(info => info.userContextId == userContextId);
   },
 
@@ -122,3 +232,5 @@ this.ContextualIdentityService = {
     }
   },
 }
+
+ContextualIdentityService.init();