Marijuana use and violent behavior are causing widespread public concern. This article reviews theory and research on the relation between marijuana use and aggressive/violent behavior. It is evident from the inconsistent findings in the literature that the exact nature of the relation remains unclear. This article identifies several possible reasons for these contradictory findings and provides suggestions for future research. In particular, more research is needed on the different subtypes of aggressive behavior. Further research is also needed to elucidate the associations between gender, marijuana use, and violent behavior. Likewise, an important task for future research is to continue to tease apart the complex relations between gang involvement, marijuana use, and violent behavior. Longitudinal studies also warrant further investigation. Moreover, future research should control for several potentially confounding variables.