One or more users may interact simultaneously with different applications on the same device through an input system such as a touch-sensitive display screen. Simultaneous user input may be detected by a multiple input system and subsequently transmitted to an application using a single transmission frame. An application corresponding to the user input is determined based on an input location of the user input and a location and size of a corresponding application. Simultaneous user inputs are rendered simultaneously by each corresponding application. Each application may further include a secondary event processing thread that runs in parallel to traditional operating system event threads. The secondary event processing thread bypasses sequential processing limits of an operating system event thread, providing substantially simultaneous processing of input.