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-Ueffect 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 < 0.0001. 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 < 0.0001. 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.