This paper takes an institutional perspective on the topic of sustainability in order to analyse how this "idea" enters science teacher education through an interdisciplinary approach. It shows how the development and implementation of a course for Danish pre-service teachers was conditioned and constrained by a complex web of interactions in and among the teaching disciplines of biology, geography and physics/chemistry and among the institutions of school, teacher college and university. The data collected are used to identify influences among the disciplines as well as disciplinary differences, conceptualised through a new reference model that separates the analysis from the usual sustainability dimensions. The findings reveal how sustainability as a teaching topic can be a unifying idea in an interdisciplinary setting. Disciplinary differences evidently impact course planning and implementation significantly, but not exclusively. By elaborating on the interactions between these circumstances, the paper provides insight into the processes of developing interdisciplinary teacher education.