School principals play critical roles in the educational and emotional growth of their students. The role of the principal continues to become more complex, with an increasing list of requirements from the various constituents they seek to serve. To foster their growth and development, school districts often offer structures of support to assist principals in successfully approaching their diverse responsibilities and experiencing satisfaction in their work. This research study considered principal supervision as a systematic strategy of support, examining various models of principal supervision across several Southern California school districts. The researcher sought to examine the district level structures and practices used to support principal supervisors in their efforts to advance principals’ instructional leadership knowledge and skills. The study also looked to uncover the various types of successful supervision practices they utilized in their support of principals. The findings of this study suggest that principal supervisors play important roles in ensuring principals gain the knowledge and skills needed to lead instruction, manage personnel, budgets, and facilities, and create supportive systems for teachers’ ongoing professional growth. Study findings include information on the district leaders serving as principal supervisors, their professional learning, and supports or barriers they encountered that assisted or hindered their work. Findings also include information regarding the degree to which districts utilized performance standards in the developing systems for evaluating principal supervisors and whether districts evaluated them on their support of principals. Further findings include where the support of principals ranked within the broad scopes of supervisors’ responsibilities.