The most important lesson learned about interpersonal violence in the past 20 years is the astonishingly high prevalence of sexual assault in American society. The extensiveness of unreported sexual assault has been repeatedly documented through the use of self-report data from well-constructed surveys of victims and perpetrators. In contrast, little has been learned about how to effectively reduce rates of sexual assault perpetration. Theoretically derived universal prevention programs targeted at adolescents are sorely needed.