Purpose: The purpose of this project was to explore the developmental stages of a community of practice (CoP) and its impact on teachers' professional learning. Methods: Eight physical education (PE) teachers and one professor participated in this project, which specifically examined a CoP focused on PE (PE-CoP). Interviews and observations, as well as a focus group, were used to collect the data, which were analyzed through a constructivist revision of grounded theory. Results: The PE-CoP, which shared the same teaching model, progressed rapidly in its early stage by providing the teachers with collaborative activities to develop innovative pedagogies. Learning from the existing members was then added as a main type of professional learning for the teachers. The PE-CoP, however, gradually lost its collaborative approach, which led to ineffective professional learning. Conclusions: Finding an optimal balance between retaining focus on the primary goal of creating a CoP and offering fresh activities for more experienced members was determined to be a key factor in making the community healthy and sustainable.