Students' cooperative and prosocial behavior is vital to their social and academic success and to the quality of a school's social environment. This project will evaluate an instructional technique that could benefit students and schools by encouraging higher levels of prosocial behavior among students and promoting social integration and inclusion, particularly for marginalized students. The instructional technique is called "cooperative learning" which involves students working in groups toward shared academic goals. Previous research indicates that cooperative learning promotes social acceptance and increases academic engagement and achievement. However, it has not been evaluated as a technique to reduce student behavioral problems and promote greater school safety. There is strong reason to believe that it will have these benefits, since cooperative learning brings together students from diverse social groups and provides them the opportunity to work together toward shared goals in a positive setting.