Evaluation of the Olweus Bullying Prevention Program in US Urban Middle Schools Using a Multiple Baseline Experimental Design.

We evaluated the impact of the Olweus Bullying Prevention Program (OBPP) in an 8-year study in urban middle schools that served primarily African American students living in low-income areas. Participants included 2755 students and 242 teachers. We evaluated the OBPP with a multiple-baseline experimental design where the order and intervention start time was randomly assigned for each school. We assessed the frequency of bullying behaviors and experiences including physical, relational, and verbal aggression and victimization using teacher ratings of student behavior and student-reported data, as well as cyber aggression and victimization and school climate measures using student-reported data. For teacher ratings of student behavior, we found significant main effects across all subtypes of aggression and victimization, with some variability in the timing of effects. The pattern of findings showed delayed intervention effects for boys and a weaker impact of the OBPP on 6th graders. We found main effects for student-reported cyber aggression and victimization, relational aggression, and a composite of physical, verbal, and relational victimization. Decreases in victimization emerged in the 1st or 2nd year of intervention, and reductions in aggression emerged during the 3rd year. Across all findings, once intervention effects emerged, they remained significant in subsequent intervention years. The OBPP resulted in significant decreases in student- and teacher-reported aggression and victimization. However, this intervention had limited impact on general areas of school climate including teacher support, positive peer interactions, and school safety. Overall, the findings offer important prevention and research implications.