Since the mid-1990s, research on interpersonal acceptance and exclusion has proliferated, and several paradigms have evolved that vary in their efficiency, context specificity, and strength. This article describes one such paradigm, Cyberball, which is an ostensibly online ball-tossing game that participants believe they are playing with two or three others. In fact, the "others" are controlled by the programmer. The course and speed of the game, the frequency of inclusion, player information, and iconic representation are all options the researcher can regulate. The game was designed to manipulate independent variables (e.g., ostracism) but can also be used as a dependent measure of prejudice and discrimination. The game works on both PC and Macintosh (OS X) platforms and is freely available.