 This cluster-randomized school-based study will examine the effectiveness of a program for the primary prevention of perpetration of teen dating violence and sexual violence among middle school male athletes. Engaging men and boys in preventing violence against women and girls is recognized by major global health organizations as a critical public health strategy. Coaching Boys into Men is a theory- and evidence based program intended to alter gender norms that foster teen dating violencesexual violence perpetration, promote bystander intervention, and reduce teen dating violencesexual violence perpetration. Coaches receive a 60-minute training and biweekly check-in from a violence prevention advocate to administer the intervention to their athletes via 12 mini-lessons conducted weekly throughout a sport season. In a randomized trial of program effectiveness among high school athletes Centers for Disease Control and Prevention CE001561-01, PI Miller, male athletes receiving the program demonstrated increased positive bystander intervention behaviors and less verbal abuse perpetration compared to controls. This project seeks to test the effectiveness of this program with younger male athletes in grades 6-8.The innovations are three-fold: 1 testing the efficacy of a novel teen dating violencesexual violence prevention program for middle school male athletes; 2 training athletic coaches in Teen Dating ViolenceSexual Violence prevention thus implementing primary prevention that does not rely on teachers or classroom time; and 3 integrating the goal of changing gender norms with the technique of a bystander intervention approach to reduce teen dating violencesexual violence prevention. The experimental design involves a 2-armed cluster randomized- controlled trial in 41 middle schools 38 clusters in Pennsylvania. Schools will be randomly assigned to either intervention or control standard coaching condition. Coaches in intervention schools will receive Coaching Boys into Men training. Baseline surveys will be collected for all intervention and control site athletes entering grades 6-8 at the start of each sports seasons across Year 1 Time 1; N 973 athletes. Follow up surveys will be collected at the end of each sports season Time 2. All participating athletes will be re-surveyed 12 months after baseline Time 3. 