A method, comprising: at an electronic device having one or more processors, memory, a touch-sensitive surface, and a display: displaying a messaging user interface of a messaging application on the display, the messaging user interface including a conversation transcript of a messaging session between a user of the electronic device and at least one other user, and an application affordance; while displaying the messaging user interface, detecting an input that activates the application affordance; in response to detecting the input that activates the application affordance, maintaining display of the conversation transcript and concurrently displaying a launch icon for an application store and a plurality of launch icons for interactive applications operable within the messaging application, wherein activation of any respective launch icon of the plurality of launch icons launches a corresponding interactive application for display within the messaging application; detecting an input that activates the launch icon for the application store; in response to detecting the input that activates the launch icon for the application store: ceasing to display the messaging user interface, and displaying an application store user interface, including display of a plurality of interactive applications, the plurality of interactive applications comprising only interactive applications operable within the messaging application and available for download to the electronic device; while displaying the application store user interface, detecting an input that corresponds to a request to download a first interactive application selected from the plurality of applications that is not stored in the memory of the electronic device; and, in response to detecting the input that corresponds to the request to download the first interactive application: downloading the first interactive application to the memory of the electronic device; replacing display of the application store user interface with display of the messaging user interface, the messaging user interface including the conversation transcript and at least some of the plurality of launch icons for interactive applications; and adding a launch icon that corresponds to the first interactive application to the display of the plurality of launch icons for interactive applications. displaying a messaging user interface of a messaging application on the display, the messaging user interface including a conversation transcript of a messaging session between a user of the electronic device and at least one other user, and an application affordance; while displaying the messaging user interface, detecting an input that activates the application affordance; in response to detecting the input that activates the application affordance, maintaining display of the conversation transcript and concurrently displaying a launch icon for an application store and a plurality of launch icons for interactive applications operable within the messaging application, wherein activation of any respective launch icon of the plurality of launch icons launches a corresponding interactive application for display within the messaging application; detecting an input that activates the launch icon for the application store; in response to detecting the input that activates the launch icon for the application store: ceasing to display the messaging user interface, and displaying an application store user interface, including display of a plurality of interactive applications, the plurality of interactive applications comprising only interactive applications operable within the messaging application and available for download to the electronic device; ceasing to display the messaging user interface, and displaying an application store user interface, including display of a plurality of interactive applications, the plurality of interactive applications comprising only interactive applications operable within the messaging application and available for download to the electronic device; while displaying the application store user interface, detecting an input that corresponds to a request to download a first interactive application selected from the plurality of applications that is not stored in the memory of the electronic device; and, in response to detecting the input that corresponds to the request to download the first interactive application: downloading the first interactive application to the memory of the electronic device; replacing display of the application store user interface with display of the messaging user interface, the messaging user interface including the conversation transcript and at least some of the plurality of launch icons for interactive applications; and adding a launch icon that corresponds to the first interactive application to the display of the plurality of launch icons for interactive applications. downloading the first interactive application to the memory of the electronic device; replacing display of the application store user interface with display of the messaging user interface, the messaging user interface including the conversation transcript and at least some of the plurality of launch icons for interactive applications; and adding a launch icon that corresponds to the first interactive application to the display of the plurality of launch icons for interactive applications.