This article reports on a qualitative case study investigating a multi-year, professional development as a form of community of practice (CoP). Data were collected over 4 years and included pre-post surveys, field notes, and archival data. Findings suggest a refinement of the CoP framework to include the existence of micro-communities of practice (MCoP). MCoPs only exist as areas of specialisation within a larger, complex CoP. We describe the emergence of two such micro-communities and propose the phenomenon needs further research.