The present meta-analysis evaluated the effectiveness of bystander education programs for preventing sexual assault in college communities. Undergraduates trained in bystander education for sexual assault were expected to report more favorable attitudes, behavioral proclivities, and actual behaviors relative to untrained controls. Data from 12 studies of college students (N = 2,926) were used to calculate 32 effect sizes. Results suggested moderate effects of bystander education on both bystander efficacy and intentions to help others at risk. Smaller but significant effects were observed regarding self-reported bystander helping behaviors, (lower) rape-supportive attitudes, and (lower) rape proclivity, but not perpetration. These results provide initial support for the effectiveness of in-person bystander education training. Nonetheless, future longitudinal research evaluating behavioral outcomes and sexual assault incidence is needed.