Immersive virtual environment technology (IVET) allows developers to create simulated environments that can engage users in context relevant behaviors and that can produce relatively intense user experiences for purposes such as entertainment (e.g., video games), phobia desensitization, and training. We predicted that playing a violent video game using an IVET platform would lead to increased presence and aggressive feelings and behavior compared to playing on a less immersive desktop platform. The results of two experiments supported this hypothesis. The data suggest that presence mediated the relationship between playing platform and aggressive feelings but not the relationship between playing platform and aggressive behavior. Finally, we explored the utility of using cardiovascular measures within this research paradigm.