Maladaptive behaviors include actions that detract from instructional time, place a larger financial burden on the school district, and create an unsafe learning environment for all students. This study was done to determine the effectiveness of Positive Behavioral Interventions and Supports (PBIS) in reducing maladaptive behavior in public school systems. A meta-analysis was conducted and included 19 empirically-based studies that addressed this topic. Each study was coded for eight moderator variables, which influenced the overall effectiveness of each PBIS program. Results of this meta-analysis show that PBIS programs for adolescents that are implemented daily at a district wide level and include assessments of fidelity, were most effective in reducing maladaptive behaviors. When school districts select PBIS programs, they should consider these characteristics of effective programs.