The published single-case design (SCD) research (N = 19 articles) on self-monitoring and reading performance was synthesized. The following inclusion criteria were used: (a) the study must have been peer-reviewed, (b) implemented an intervention targeting student self-monitoring of reading skills, (c) included data on at least 1 reading outcome, (d) included visual representation of the data, and (f) the study must have used an SCD to assess the topic of interest. A total of 67 participants, 45 males and 22 females, ranging in age from 7:8 −18:7 were included in the current meta-analysis. Ethnicity was reported for 42 students: 23 were Caucasian, 12 were African American, and 7 were Latino/Hispanic. Studies were compared with those meeting What Works Clearinghouse (WWC) standards and those not meeting standards. The Tau-U effect size (ES) method was the main calculation method used; however, Phi ES estimates are included for comparison purposes. Results indicated that self-monitoring had an overall significant large positive effect on the reading performance of K–12 students, Tau-U = 0.79, 95% confidence interval (CI) [0.64, 0.93], p < .0001. However, self-monitoring for studies that met WWC criteria yielded a larger overall positive ES, Tau-U = 0.93, 95% CI [0.79, 1.07], p < .0001. Although the current meta-analysis is limited to peer-reviewed SCD studies, the findings provide support for self-monitoring as an evidence-based reading intervention for students in Grades K–12. Furthermore, findings indicate that larger ES values were identified when consolidating studies based on WWC guidelines as compared with consolidating across all studies.