Researchers in both Japan and in the United States have documented that bullying is a common and potentially damaging form of violence among children. The authors' review highlights distinct cross-cultural patterns of personal, family, peer, and school characteristics that predict gender differences in bullying and victimization. Cross-cultural patterns confirm that bullying has detrimental and long-lasting effects on both the bullies and their victims. School-based prevention/intervention programs have had mixed success, mainly because some of the risk factors associated with bullying and victimization are beyond the scope of these programs. Bullying and victimization are sometimes associated with psychological disorders and a history of family violence. In these cases, therapeutic intervention is required. Family therapists and other mental health professionals need to be aware of cultural variations in bullying and work collaboratively with schools and families to develop effective treatment plans.