Peer tutoring is an instructional strategy that involves students helping each other learn content through repetition of key concepts. This meta-analysis examined effects of peer tutoring across 26 single-case research experiments for 938 students in Grades 1-12. The TauU effect size for 195 phase contrasts was 0.75 with a confidence interval of CI[subscript 95] = 0.71 to 0.78, indicating that moderate to large academic benefits can be attributed to peer tutoring. Five potential moderators of these effects were examined: dosage, grade level, reward, disability status, and content area. This is the first peer tutoring meta-analysis in nearly 30 years to examine outcomes for elementary and secondary students, and extends previous peer tutoring meta-analyses by examining disability as a potential moderator. Findings suggest that peer tutoring is an effective intervention regardless of dosage, grade level, or disability status. Among students with disabilities, those with emotional and behavioral disorders benefitted most. Implications are discussed. (Contains 1 figure and 2 tables.)