We randomly assigned the Shifting Boundaries interventions to 30 public middle schools in New York City, enrolling 117 sixth and seventh grade classes (over 2,500 students) to receive a classroom, a building, a combined, or neither intervention. The classroom intervention included a six-session curriculum emphasizing the laws and consequences for perpetrators of dating violence and sexual harassment (DV/H), the social construction of gender roles, and healthy relationships. The building-based intervention included the use of building-based restraining orders, higher levels of faculty/security presence in safe/unsafe “hot spots” mapped by students, and posters to increase DV/H awareness and reporting. Student surveys were implemented at baseline, immediately after the intervention, and 6-months post-intervention. As hypothesized, behaviors improved as a result of the interventions. The building-only and the combined interventions were effective in reducing sexual violence victimization involving either peers or dating partners at 6-months post-intervention. This was mirrored by reductions in sexual violence perpetration by peers in the building-only intervention. While the preponderance of results indicates that the interventions were effective, an anomalous result (increase in sexual harassment victimization reports that was contradicted by lower frequency estimates) did emerge. However, after analysis these anomalous results were deemed to be most likely spurious. The success of the building-only intervention alone is important because it can be implemented with very few extra costs to schools.