Purpose: The purpose of this study was to examine the ways principals in three high-needs middle schools enacted core leadership practices in concert with their immediate contexts to institutionalize comprehensive school reforms and support student learning. Research Methods: The schools were selected from a geographically stratified sample of public middle schools in a state in the southeastern United States. Multiple linear regression was used to identify schools performing better than expected considering their levels of poverty and other school-related factors. The final three schools, one from each geographic region, showed steady increases in academic achievement and school climate following the arrival of their principals. Data were primarily collected from interviews with principals, teaching and nonteaching staff, and parents using protocols adapted from the International Successful School Principalship Project. Findings: The findings explicate the large degree to which the leadership practices and beliefs that influenced student achievement in these schools were adapted to and commensurate with each school’s immediate context. Furthermore, they illustrate how principals used these practices to institutionalize school-wide reform efforts as vehicles for leading change within their schools. Implications: The findings substantiate research on successful school leadership in high-needs middle schools. They also extend this research by examining the way core transformational and instructional leadership practices can be adapted to suit various school contexts and institutionalize school-wide reform efforts to enhance student learning. Further research is required to understand how principals decide to adapt their leadership practices, and how aspiring leaders can best learn to do so.