diff --git a/index.js b/index.js
index 5a45c07..a751559 100644
--- a/index.js
+++ b/index.js
@@ -43,7 +43,10 @@ let ContainerService = {
       "openTab",
       "moveTabsToWindow",
       "queryIdentities",
-      "getIdentity"
+      "getIdentity",
+      "createIdentity",
+      "removeIdentity",
+      "updateIdentity",
     ];
 
     // Map of identities.
@@ -164,10 +167,14 @@ let ContainerService = {
   // Tabs management
 
   hideTabs(args) {
-    return new Promise(resolve => {
+    return new Promise((resolve, reject) => {
+      if (!("userContextId" in args)) {
+        reject("hideTabs must be called with userContextId argument.");
+        return;
+      }
+
       for (const tab of tabs) {
-        const userContextId = this._getUserContextIdFromTab(tab);
-        if ("userContextId" in args && args.userContextId !== userContextId) {
+        if (args.userContextId !== this._getUserContextIdFromTab(tab)) {
           continue;
         }
 
@@ -180,6 +187,11 @@ let ContainerService = {
   },
 
   showTabs(args) {
+    if (!("userContextId" in args)) {
+      Promise.reject("showTabs must be called with userContextId argument.");
+      return;
+    }
+
     let promises = [];
 
     for (let url of this._identitiesState[args.userContextId].hiddenTabUrls) {
@@ -367,10 +379,57 @@ let ContainerService = {
   },
 
   getIdentity(args) {
+    if (!("userContextId" in args)) {
+      Promise.reject("getIdentity must be called with userContextId argument.");
+      return;
+    }
+
     let identity = ContextualIdentityService.getIdentityFromId(args.userContextId);
     return Promise.resolve(identity ? this._convert(identity) : null);
   },
 
+  createIdentity(args) {
+    for (const arg of [ "name", "color", "icon"]) {
+      if (!(arg in args)) {
+        Promise.reject("createIdentity must be called with " + arg + " argument.");
+        return;
+      }
+    }
+
+    // FIXME: icon and color conversion based on FF version.
+    const identity = ContextualIdentityService.create(args.name, args.icon, args.color);
+    return Promise.resolve(this._convert(identity));
+  },
+
+  updateIdentity(args) {
+    if (!("userContextId" in args)) {
+      Promise.reject("updateIdentity must be called with userContextId argument.");
+      return;
+    }
+
+    let identity = ContextualIdentityService.getIdentityFromId(args.userContextId);
+    for (const arg of [ "name", "color", "icon"]) {
+      if ((arg in args)) {
+        identity[arg] = args[arg];
+      }
+    }
+
+    // FIXME: icon and color conversion based on FF version.
+    // FIXME: color/name update propagation
+    return Promise.resolve(ContextualIdentityService.update(args.userContextId,
+                                                            identity.name,
+                                                            identity.icon,
+                                                            identity.color));
+  },
+
+  removeIdentity(args) {
+    if (!("userContextId" in args)) {
+      Promise.reject("removeIdentity must be called with userContextId argument.");
+      return;
+    }
+    return Promise.resolve(ContextualIdentityService.remove(args.userContextId));
+  },
+
   // Styling the window
 
   configureWindow(window) {