A program guide system is provided that supports a program guide application and multiple non-guide applications. The program guide system has a program guide application interface that allows the non-guide applications to use both device resources and program guide resources. The application interface maintains a list of registered applications and directs control requests from various applications to the current primary application. The application interface also has a user interface input director that directs keystrokes and other user input commands to the appropriate application. If a keystroke for the program guide application is detected while a non-guide application is running, the program guide application is invoked.