Interdisciplinary research is gathering increasing support from sustainability scholars, however, there is little dialogue between scholarship on interdisciplinarity and interdisciplinary environmental science education. The aim of this paper is to take stock of the insights of studies of interdisciplinary research to inform environmental research and education. We take as our case study a research centre in Spain, which created an interdisciplinary PhD programme on climate change. The analysis is based on 18 interviews with PhD students and supervisors. We focus on: (1) the need to train experts while redefining expertise outside of disciplinary boundaries; (2) the practical and institutional challenges of interdisciplinarity in the context of PhD training; and (3) the challenges of assessing the quality across disciplines. Our results show that conflicts with institutional requirements lead to a tendency to abandon interdisciplinary aspects and to the training of experts narrowly centred on the specific problem they analyse.