The negative outcomes of exclusionary discipline practices on children and youth are well established. Fortunately, for the past two decades, research has demonstrated that pro-active instructional approaches and building supportive class and school environments can effectively promote student social, emotional, and behavioral well-being, especially when evidence-based practices are placed within a problem-solving multitiered system of supports such as school-wide positive behavioral interventions and supports (SWPBIS). Recent work examining state-wide behavioral interventions and supports (PBIS) initiatives, which include professional development and technical assistance to school leadership teams, has clearly documented that educators can reduce problem behavior and thereby reduce the need or use for exclusionary discipline practices. This study extends that body of knowledge by examining Missouri's SWPBIS initiative over time and across grade levels. Using an extant data base, schools implementing SWPBIS with fidelity were compared with nonimplementing schools over 11 school years. Results indicated that schools implementing SWPBIS with fidelity had statistically significant lower rates of exclusionary discipline practices at the primary, middle, and high school level. Results are discussed within the context of past state-wide SWPBIS initiatives.