The "Self-Assessment and Program Review" (SAPR) was developed to provide an assessment tool that schools could use to track their progress in implementing key practices related to all three levels of schoolwide positive behavior supports (SWPBS). The SAPR is a team-based assessment tool, using both individual and team ratings of 10 evidence-based subscales and related indicators, to monitor the implementation of SWPBS practices and assist teams in developing and monitoring plans for school improvement. This article describes the background, development, features, and details of the initial psychometric properties of the measure. The role and function of the SWPBS leadership team were also analyzed for their influence on the assessment and implementation process. Overall, results suggest that the SAPR is both reliable and valid, and it provides a useful and efficient tool to leadership teams interested in assessing their implementation of key SWPBS practices. (Contains 9 tables.)