This meta-analysis examined the effects of self-assessment (SA) and/or peer-assessment (PA) interventions on academic performance. The synthesis included 626 effect sizes from 175 inde-pendent studies, either using an experimental/quasi-experimental design or a repeated measures design, and involved 19,383 participants in total. Results indicated that SA (g = 0.585), PA (g = 0.606), and SA + PA (mixed) intervention (g = 0.448) had meaningful effects on academic performance. The difference between the effects of SA and PA interventions, conducted on different groups within the same study, was not statistically significant. The use of online tech-nology increased the effect of PA interventions but not for SA. Participants with a higher mean age had more performance gains from the SA + PA (mixed) intervention. For both SA and PA, the studies that used a repeated measures design generated larger effect sizes than those with an experimental/quasi-experimental design. Overall, the findings from this meta-analysis demon-strated the benefits of SA and PA interventions on academic performance in different contexts. Implications for practice and directions for future research are discussed.