Problem Statement: Literature reviews clearly document that students still show a tendency to use violence in resolving interpersonal conflicts in school. Results from various research conducted in Turkey suggest that violence, aggression, and bullying behaviors are still rampant in the primary and high schools. Studies conducted in primary and middle schools toward decreasing aggression and preventing violence focus on programs such as violence prevention, conflict resolution, and peer mediation. While these programs are mainly based on peacemaking strategy, prevention programs based on positive peace and peacebuilding strategy with tested effectiveness are rather limited. Thus, a peace education program based on positive peace and peacebuilding strategy was developed and its effects on aggression levels of sixth grade students were investigated.