This investigation employed a participatory action research method involving school psychology consultants and educators to design and evaluate the impact of school-wide positive behavioral interventions and supports in a self-contained school serving students with emotional and behavioral disorders. The traditional practices of a universal system, including teaching and acknowledging expected behaviors and responding to disruptive behaviors, were adapted to better accommodate the needs of a more challenging student population. In addition, system-wide practices, including various teaming and professional development strategies, were instituted to promote sustainability. Results, after implementation of Tier 1, showed reductions in the frequency of discipline referrals and the number of emergency safety interventions, with a sustained impact across the next 3 years. Limitations included the lack of experimental control in evaluating the intervention. Discussion includes recommendations for an expanded role for school psychologists in promoting evidence-based practices for high-risk student populations.