Positive Behavioral Interventions and Supports (PBIS) is a universal, school-wide prevention strategy that is currently implemented in over 7,500 schools across the nation to reduce disruptive behavior problems through the application of behavioral, social learning, and organizational behavioral principles. PBIS aims to alter school environments by creating improved systems and procedures that promote positive change in student behavior by targeting staff behaviors. The present study examined the impact of PBIS on school organizational health using data from a large randomized controlled trial of PBIS conducted in 37 elementary schools. Longitudinal multilevel analyses on data from 2,507 staff revealed a significant effect of PBIS on staff reports of the schools' overall organizational health, resource influence, and staff affiliation over a 3-year period. This study indicated that changes in school organizational health are important consequences of the PBIS whole-school prevention model, and might in turn be a potential mediator of the effect of PBIS on student performance.