Bullying and peer victimization are increasingly recognized as a detriment to the well-being of students. While the past two decades have seen the development of several effective approaches to prevention at the elementary and middle school levels, very little research has documented effective strategies for students in high schools. The current study evaluated a simple, student-led intervention called Stand for Courage (SfC), conducted across six high schools in the Mountain West, to determine the relationship between the implementation of SfC and the reduction of self-reported victimization and perpetration. Results of the one year study indicated that following intervention, students in SfC schools were 51.9% less likely to report victimization and 53.8% less likely to report perpetration compared to students in control schools. Additional chi-square analyses also determined that victimization and perpetration differed significantly between treatment groups by location, victim response, and peer response. Implementation fidelity of intervention components remained high across the study, and both adults and students within the study reported the intervention was both effective, efficient, and worth their time and effort. While limitations exist, the results of this study provide powerful evidence for the effectiveness of simple, student led prevention strategies in high schools.