Schoolwide Positive Behavioral Interventions and Supports (SWPBIS) is a universal, schoolwide prevention strategy that is currently implemented in over 9,000 schools across the nation to reduce disruptive behavior problems through the application of behavioral, social learning, and organizational behavioral principles. SWPBIS aims to alter school environments by creating improved systems and procedures that promote positive change in student behavior by targeting staff behaviors. This study uses data from a 5-year longitudinal randomized controlled effectiveness trial of SWPBIS conducted in 37 elementary schools to examine the impact of training in SWPBIS on implementation fidelity as well as student suspensions, office discipline referrals, and academic achievement. School-level longitudinal analyses indicated that the schools trained in SWPBIS implemented the model with high fidelity and experienced significant reductions in student suspensions and office discipline referrals. (Contains 1 table and 5 figures.)