Purpose: The purpose of this study was to explore high school administrators' instructional leadership in math and science. Specifically, the study explored the feedback administrators provided to math and science teachers as part of their instructional supervision. A central goal for this study was to determine how differences in these content areas influenced the feedback administrators provided to teachers. Research Method/Approach: The study was completed in five, comprehensive high schools located in the western United States. A multicase qualitative research design was used to complete this investigation. The study included more than 50 individual participants, including school administrators and classroom teachers. Findings: Three themes were produced from the analysis. First, the feedback administrators provided to teachers focused on pedagogy as opposed to their content understanding. Second, administrators provided feedback that was anchored within their past experience as teachers. This experience shaped how they viewed instruction in math and science. Third, administrators sought ways to make their feedback more meaningful and saw student assessment data as a useful strategy. Conclusions: School administrators' feedback to classroom teachers about their instruction appears bound within distinct subject subcultures that stem from their past experience as classroom teachers. It is therefore incumbent on administrators to learn how to work across these cultures to support schoolwide instructional improvement. Administrators must recognize how their own position within a particular subject subculture influences the feedback they provide to classroom teachers.