Schools are frequently seen as the solution to social problems, and recent public health issues such as the near epidemic rates of obesity and diabetes are some of the newest pressures facing schools. This investigation is an exploration of physical education teachers' reactions to one school district's attempts to mandate a public health driven curricular change. Forty-six elementary physical education teachers reported via interviews their perceptions of the change process. Data were analysed via a constant comparison process. Two key areas of implementation challenges were identified; including teachers' need for new knowledge and the mismatch between the curriculum and teachers' understanding of physical education and their context.