Abstract
Commensurate with the serious risks bullying poses to students’ mental health, substantial attention has been devoted to evaluating school bullying prevention programs. Research on the effectiveness of these interventions shows mixed outcomes. Recent evidence suggests that even programs that reduce overall bullying may have negative outcomes for victims. Most bullying prevention programs incorporate a range of strategies, but we know little about which strategies actively reduce bullying and whether some may have iatrogenic effects. Questions have been raised about programs that involve working with peer bystanders and whether some strategies stigmatize victims. In this article, I propose three theoretically derived hypotheses that describe mechanisms through which encouraging peers to actively defend victims may produce adverse outcomes for victims. More research is needed to test these hypotheses. A deeper understanding of the differential impact of bullying prevention strategies will lead to improvements in programs and more targeted use of effective strategies.