Active supervision--defined as circulating, scanning, interacting with students, and reinforcing demonstrations of expected academic and social behaviors by a teacher or other staff member--is often considered a component of safe and secure schools. Yet, the evidence base supporting the effectiveness of active supervision has not been synthesized or evaluated for its quality. Therefore, we conducted an evidence-based review and meta-analysis of empirical research evaluating the effects of active supervision in schools. We identified 12 research studies evaluating active supervision, assessed the quality of each study, and calculated effect sizes for student behaviors, including disruptive behavior. Results from the four studies meeting data requirements for estimating standardized mean difference effect sizes suggest that, on average, active supervision reduced problem behavior by almost 2.0 standard deviation units. Only four studies met the What Works Clearinghouse (WWC) design standards and the results of those were mixed, thus not meeting the WWC evidence-based criteria. Limitations and recommendations for future research are discussed.