This case study explored the perspectives of four high school principals regarding the definition of instructional supervision, the process of instructional supervision, the climate that enhances instructional supervision, what gets in the way of principals supervising teachers, and the structure of the high school. The constant comparative method of data analysis was used in this qualitative study. Drawing from the literature in the areas of the purposes and intents of instructional supervision and the history of the principal as instructional leader, the researcher examined the construct of instructional supervision within the high school setting. Results indicated that principals could not clearly articulate a definition of supervision, but rather, they defined supervision as evaluation. The factors that enhanced supervision included trust and management style. Findings indicate that due to the compartmentalized nature of the high school that the principals in this study were stymied by their inability to set priorities based on work demands and lack of expertise across specialized content areas. Other constraints included role entanglements between assistant principals, department chairs, and instructional coordinators that prevented the principals from emerging as informed instructional supervisors in their buildings. Discussion and implications are presented for principals, school systems, and leadership preparation programs in higher education.