This evaluation report presents outcomes for the first cohort of 28 early childhood education programs and K-12 schools involved in implementing schoolwide positive behavior support as part of a statewide systems change initiative that began in New Hampshire in 2002. Results indicate that the overwhelming majority of schools were able to implement schoolwide positive behavioral interventions and supports with fidelity within 2 years and to sustain implementation over the course of the following year. Implementation resulted in a reduction of 6,010 office discipline referrals and 1,032 suspensions, with middle and high schools experiencing the most benefit. These reductions helped recover 864 days of teaching, 1,701 days of learning, and 571 days of leadership. Implementation was associated with academic gains in math for the vast majority of schools who implemented with fidelity. Improvements in reading/language arts were less pervasive. Recommendations for policy, practice, and research are discussed. (Contains 1 note, 1 figure, and 3 tables.)