Objective: To assess evidence of the effectiveness of school-based education programs for the prevention of child sexual abuse (CSA). The programs deliver information about CSA and strategies to help children avoid it and encourage help seeking. Methods: Systematic review including meta-analysis of randomized controlled trials (RCTs), cluster RCTs, and quasi-RCTs. Results: Twenty-four studies with 5,802 participants were included. Child self-protective skills, odds ratio = 5.71, confidence interval = [1.98, 16.51]; factual, standardized mean difference (SMD) = 0.61 [0.45, 0.78]; and applied knowledge, SMD = 0.45 [0.24, 0.65], increased in the intervention group, and knowledge gains were retained at 6 months, SMD = 0.69 [0.51, 0.87]. There were no differences in anxiety or fear, SMD = -0.08 [0.22, 0.07], and findings regarding disclosure of abuse were inconclusive. Conclusion: Children's self-protective skills and knowledge can be increased by participation in school-based sexual abuse prevention programs. However, it is unknown whether gains in skills and knowledge actually decrease the likelihood of CSA.