The purpose of this case study was to expand the literature base regarding the application of high school schoolwide positive behavior support in an urban setting for practitioners and policymakers to address behavior issues. In addition, the study describes the use of the Change Point Test as a method for analyzing time series data that are dependent in nature. The authors used an existing case study example to guide the implementation of the intervention. The overall implementation of positive behavior support reached full fidelity during the final year. Focused professional development may have been related to changes in statistically significant office discipline referral trends. Implications for practice, future research, and policies are addressed. (Contains 1 figure, 2 tables and 4 notes.)