Eating disorder prevention programs have yielded mixed results and are somewhat controversial, primarily because of claims they may produce iatrogenic effects. We used meta-analysis to evaluate the effectiveness of eating disorder prevention programs and investigate moderators of intervention effects. Overall, prevention programs had large effects on improving knowledge and small net effects on reducing maladaptive eating attitudes and behaviors. Studies targeting participants at a relatively higher risk for developing an eating disorder produced greater benefits. Concerns about iatrogenic effects of including psychoeducational material on eating disorders were not supported by the data. These findings challenge conclusions drawn in previous review articles regarding the ineffectiveness of prevention programs and support the ability of eating disorder prevention programs to demonstrate behavioral improvements.