By studying the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) as a community of practice and learning space for academic identity development, this paper studies the creation of environmental expertise within expert organizations. The study focuses its analysis on how IPBES through its fellowship programme contributes to academic identity development among early-career researchers, including providing new contextual references to understand what it means to engage in and balance biodiversity research, teaching, and service. The study is based on interviews with early-career researchers who participated in the production of the IPBES’s Global Assessment Report. The study shows how the IPBES fellowship programme, by introducing its fellows into the organization’s community of practice simultaneously, contributes to their academic identity development and the creation and maintenance of the boundaries of environmental expertise. The analysis further shows how the fellows develop an academic identity that unites two different communities of practice of equal importance for their understanding of what they are supposed to do as academics and widens their understanding of what it means to be a successful academic.