Examining the Effectiveness of School-Bullying Intervention Programs Globally: a Meta-analysis

This article presents results from an extensive systematic and meta-analytical review of the effectiveness of school-based bullying prevention programs. Its main aim is to explore the results of this meta-analysis specifically in regard to variations in the effectiveness of school-bullying programs globally and the effectiveness of specific anti-bullying programs. Our meta-analysis included 100 independent evaluations, and found that, overall, programs were effective in reducing school-bullying perpetration and victimization. In the present paper, we focused on 12 countries (e.g., Italy, Norway, USA, UK), three regions (i.e., Europe, North America, and Scandinavia) and four anti-bullying programs (i.e., KiVa, NoTrap!, OBPP, and ViSC) with multiple evaluations. Our results showed that anti-bullying programs evaluated in Greece were the most effective in reducing bullying perpetration, followed by Spain and Norway. Anti-bullying programs evaluated in Italy were the most effective in reducing bullying victimization, followed by Spain and Norway. Evaluations conducted in North America were the most effective in reducing bullying perpetration, and evaluations conducted in Scandinavia were the most effective in reducing bullying victimization. Evaluations of the Olweus Bullying Prevention Program produced the largest effect sizes for bullying perpetration outcomes, but the NoTrap! Program was the most effective in reducing bullying victimization. We also systematically review the core components of the intervention programs and make recommendations for researchers, practitioners, and policy makers.