While teacher identity has been conceptualized in different ways, research in teacher education has shown that the development of self-understanding about being a teacher is critical to learning how to teach and can be shaped in multiple ways. Etienne Wenger argues that the formation of communities of practice is influenced strongly by the negotiation of identity and thus, to understand learning in relation to identity formation and communities of practice, three modes of belonging should be considered. Using data from a three-year action research project, the author examines how modes of belonging (engagement, alignment, and imagination) were enacted in teacher-centred action research communities of practice. As well, an ecological perspective is adopted to provide insight into how teachers' identities are formed and reformed in the context of teacher-centred action research.