<p>There is mixed evidence regarding the effectiveness of dialectical behavior therapy (DBT) skills when delivered as a universal, school-based intervention. The present study synthesized literature examining the effect of school-based DBT skills programs on adolescents’ psychosocial functioning. Two databases were searched to identify studies using single-arm trial or controlled trial designs. A random effects meta-analysis was conducted to measure the effect of school-based DBT skills interventions. Twenty-seven studies (<i>k</i> = 10 single-arm; <i>k</i> = 17 controlled) representing 4,228 participants were identified. Forty-four percent of studies were conducted with college students, and participants’ mean age was 17.83 years. Most participants were females/girls/women (69.4%) and White/Caucasian (59.4%). Results from single-arm trials suggested that DBT skills significantly improved positive psychosocial functioning (e.g., adaptive coping, life satisfaction, resilience, self-efficacy) at post-treatment and follow-up. DBT skills significantly reduced negative psychosocial functioning (e.g., maladaptive coping, emotion regulation difficulties, psychological distress) at post-treatment and follow-up. Results from controlled trials demonstrated that DBT skills significantly improved positive psychosocial functioning at post-treatment relative to controls, with no significant between-group differences at follow-up. DBT skills significantly reduced negative psychosocial functioning at follow-up, relative to controls, with no significant between-group differences at post-treatment. Analyses revealed high risk of bias within primary studies and substantial heterogeneity in effect size estimates. However, the small number of eligibles studies precluded exploration of moderator variables that may affect intervention effectiveness. In sum, DBT skills represent a promising school-based intervention for improving adolescents’ psychosocial functioning, but programs are not reliably efficacious.</p>