The purpose of this study was to examine how one secondary physical education teacher understood gender at her school and how that understanding developed. Theoretical perspectives on feminism and the nature of teachers' knowledge guided the inquiry. Data were collected through 20 teacher observations and 60 interviews over 4 months and analyzed using constant comparison with frequent member checks to facilitate accuracy. Three main findings emerged. First, this teacher identified two aspects of the broader school culture, which she believed sent students, particularly girls, gendered and patriarchal messages of social positions. Second, she described a number of practices in the traditional physical education program, which she believed contributed further to girls' disempowerment. Finally, this teacher's stance in the political structure of the school both constrained and enhanced the development of her understanding of gender. Findings are discussed in relation to feminist theoretical stances and feminist teacher knowledge development.