School principals are responsible for leadership toward meeting an academic mission predicated on student achievement in core subjects. Socialization experiences of principals relative to physical education (PE) may impact their perception of PE's academic value. Our purpose was to investigate the development and maturation of school principals’ perspective of the value of PE to their school’s academic mission. Eleven principals completed two in-depth interviews about their perception of PE's value to their school's academic mission. Interviews occurred prior to and following their PE teacher participating in extended professional development. Principals observed and assessed the teaching performance of their current PE teacher on two separate occasions between interviews. Occupational Socialization Theory guided inquiry and analysis. Principals’ positive and negative experiences during K-12 influenced their beliefs about the value of PE to the academic mission and were evident in performance expectations of their respective PE teacher. Professional training had little effect, but instructional leadership interactions with their PE teacher impacted principals’ beliefs about PE's value to the school’s academic mission. Positive changes in principal perceptions about the academic nature of PE were noted over the course of the study. Principal preparation programs offer little guidance in supporting PE. Opportunities to observe and reflect upon best practices with PE teachers may positively alter their beliefs. More guidance on evaluating teachers of specific content areas such as PE is warranted, and PE teachers may offset marginalization by engaging their principal about best practices that align with and support the school’s academic mission.