This paper looks at questions relevant to the increasing number of teachers involved in interdisciplinary courses at university level. In particular it considers the link between the intended and the realized interdisciplinarity in teaching and how this is related to the didactical planning. Drawing on one case - an interdisciplinary master course offered three times and each time with a new design - the authors highlight some of the challenges associated with interdisciplinary teaching practice. Based on this case, the authors conclude that balancing teacher expectations with possible course outcomes, selecting and organizing course content as well as examination type, all have a massive impact on whether the intended interdisciplinarity is realized over the duration of the course.