In efforts to improve outcomes for students, state education agencies have developed systems of school improvement to identify and provide support for schools that have persistently low educational outcomes, often those with majority-Black student populations. However, such efforts have generally been ineffective in turning schools around. This article describes the effects of implementing a year-long professional development series of four full days of training based on a school-wide positive behavioral interventions and supports (PBIS) framework with an explicit focus on equity in school discipline. Results from this quasi-experimental study showed statistically significant improvements in school outcomes, including exclusionary discipline and school climate as compared with similar, nonparticipating schools. Findings are discussed in terms of using PBIS for school improvement.