In this chapter, the reader is introduced to rich user interface (UI) architectures and application development on the Raspberry Pi. Rich UIs allow for a depth of interaction with an application that is not possible with command‐line interfaces (CLIs)—in particular, the addition of graphical display elements can result in easier‐to‐use applications. Also introduced are different RPi architectures that can support rich UIs, such as general‐purpose computing, touchscreen display modules, and virtual network computing (VNC). Different software application frameworks are examined for rich UI development, such as GTK+ and Qt. The Qt framework is the focus of the discussion, largely due to its comprehensive libraries of code. An example rich UI application is developed for the RPi that uses the DHT temperature and humidity sensor from Chapter 6. Finally, a feature‐rich remote fat‐client TCP application framework is developed, along with an example that uses the same sensor.