diff --git a/messenger/messenger.d.ts b/messenger/messenger.d.ts
index b874eb356..3aacf2f88 100644
--- a/messenger/messenger.d.ts
+++ b/messenger/messenger.d.ts
@@ -1,4 +1,4 @@
-// Type definitions for Messenger.js 1.2.1
+// Type definitions for Messenger.js 1.4.0
 // Project: https://github.com/HubSpot/messenger
 // Definitions by: Derek Cicerone <https://github.com/derekcicerone>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
@@ -9,18 +9,110 @@ interface IMessenger {
 }
 
 interface Messenger {
-    post(message: Message): void;
+    /**
+     * Posts a message.
+     */
+    post(options: MessageOptions): Message;
+
+    /**
+     * Hides all messages.
+     */
     hideAll(): void;
 }
 
 interface Message {
+    /**
+     * Show the message, if it's hidden.
+     */
+    show(): void;
+
+    /**
+     * Hide the message, if it's hidden.
+     */
+    hide(): void;
+
+    /**
+     * If the message is associated with an ajax request or is counting down to retry, cancel it.
+     */
+    cancel(): void;
+
+    /**
+     * Update the message with the provided options.
+     */
+    update(options: MessageOptions): void;
+}
+
+interface MessageOptions {
+    /**
+     * The text of the message.
+     */
     message: string;
+
+    /**
+     * Hide the message after the provided number of seconds.
+     */
     hideAfter?: number;
+
+    /**
+     * Hide the message if Backbone client-side navigation occurs.
+     */
+    hideOnNavigate?: boolean;
+
+    /**
+     * A unique id. If supplied, only one message with that ID will be shown at a time.
+     */
+    id?: string;
+
+    /**
+     * Should a close button be added to the message?
+     */
     showCloseButton?: boolean;
+
+    /**
+     * Hide the newer message if there is an id collision, as opposed to the older message.
+     */
+    singleton?: boolean;
+
+    /**
+     * What theme class should be applied to the message? Defaults to the theme set for Messenger in general.
+     */
+    theme?: string;
+
+    /**
+     * "info", "error" or "success" are understood by the provided themes. You can also pass your own string, and that class will be added.
+     */
     type?: string;
 }
 
 interface MessengerOptions {
+
+    /**
+     * Extra classes to be appended to the container.
+     */
+    extraClasses?: string;
+
+    /**
+     * The maximum number of messages to show at once.
+     */
+    maxMessages?: number;
+
+    /**
+     * Default options for created messages.
+     */
+    messageDefaults?: MessageOptions;
+
+    /**
+     * Which locations should be tried when inserting the message container into the page.
+     * The default is ['body']. It accepts a list to allow you to try a variety of places
+     * when deciding what the optimal location is on any given page. This should generally
+     * not need to be changed unless you are inserting the messages into the flow of the
+     * document, rather than using messenger-fixed.
+     */
+    parentLocations?: string[];
+
+    /**
+     * What theme are you using? Some themes have associated javascript, specifing this allows that js to run.
+     */
     theme?: string;
 }