The purpose of this study was to compare the impact of participation versus observing an aggressive virtual reality game on young adults’ arousal levels, feelings of hostility, and aggressive thoughts. The major hypothesis was that physiological arousal and aggressive thoughts would increase more for those who participated directly in the virtual reality experience than for those who observed it. The arousal and social cognitive theories were expected to provide the best fit for explaining how virtual reality impacts adults’ aggressive behaviors. No support was expected for a tension-reduction hypothesis, indexed by hostile feelings, as would be predicted by the psychoanalytic theory. Gender and aggressive traits were included in order to examine differential effects of aggressive exposure on different kinds of people.