In this study, we randomly assigned 123 sixth and seventh grade classrooms from seven middle schools in the greater Cleveland area to one of two five-session curricula addressing gender violence/sexual harassment (GV/SH) or to a no-treatment control group. A baseline survey and two follow-up surveys were administered immediately after the treatment (Wave 2) and about six months posttreatment (Wave 3). In an earlier paper, we demonstrated the effectiveness of two approaches to youth GV/SH prevention programming (a fact-based, law and justice curriculum and an interaction-based curriculum). In this paper, we explored whether these largely positive findings remain for both girls and boys, including whether girls experience higher levels of GV/SH than boys. Most of our statistical models proved to be non-statistically significant. However, in 2 of our 48 victimization/ perpetration (any violence, sexual violence and non-sexual violence) models (across two post-intervention follow-up points), we observed that the interventions reduced peer (male or female, non-dating partner) sexual violence victimization and reduced peer perpetration, but another outcome model indicated that the interventions increased dating perpetration. These mixed findings will need to be explored further in future research. Regarding our primary research question, we observed no statistically significant differences for the treatment multiplied by gender interaction terms for any of the perpetration or victimization outcome models, suggesting that the treatment had similar effects on girls and boys. However, we did observe that boys are more involved in violence than girls: both as victims and perpetrators. Boys experienced significantly more of three types of victimization from peers and dating partners compared to what girls experienced at the hands of their peers and dating partners. As perpetrators, boys committed more sexual victimization against peers (immediately post-intervention only) and more sexual victimization against dating partners than girls. The implications of these results are discussed.