Abstract The effectiveness of psychological interventions has long been discussed and studied in the behavioral sciences. In recent years, the quantitative review technique of meta-analysis has been utilized to evaluate effectiveness across a wide variety of therapeutic interventions. The purpose of this study was to apply this technique to school-based outcome studies of counseling and psychotherapy published in a recent 10-year period. In particular, this study updates and extends an earlier meta-analysis focusing on the same question (Prout & DeMartino, 1986). Seventeen studies were identified that met criteria acceptable for use in a meta-analysis and were either conducted in school settings or dealt with relevant school issues or problems. The analysis found an overall effect size of nearly one standard deviation across all studies and outcome variables. These findings support the effectiveness of school-based therapeutic interventions, although this conclusion is offered with some cautions and limitations. These findings apply almost exclusively to group interventions. Further, the greatest impact was on self-report variables and variables reflective of more internal states. Cognitive-behavioral interventions appeared to have the stronger effects, with interventions with elementary students also showing greater impact. Implications for practice and directions for future research are discussed.