The aim of this article is to contribute to the understanding and use of the theory of communities of practice. In order to clarify terms, explore applications for education and reflect on various critiques of the theory in the literature, two educational researchers conducted a series of interviews with the theorist Etienne Wenger-Trayner. The interviews have been thematically organised around key concepts from the theory. By relating the concepts to their uses in research and to other social theories, Wenger-Trayner clarifies key ideas of the theory including what constitutes a "community of practice". He explains how he conceptualises identity and participation in order to develop a social theory of learning in which power and boundaries are inherent. The interviewers draw on these conceptual discussions with Wenger-Trayner to consider how the theory of communities of practice resonates with key debates and issues in education. By unpacking some key concepts of the theory from an educational perspective, we provide researchers with conceptual tools to support the complex decision-making that is involved in selecting the best and most appropriate theory or theories to use in their research.