Despite the fact that interdisciplinarity is on top of the agenda at many higher education institutions, there are few practical guidelines on which to build interdisciplinary engineering curricula. This study focused on how interdisciplinarity is perceived at TU Delft, which interdisciplinary skills are assessed in these programmes, how these are assessed and how they relate to the interdisciplinary problem being addressed. Results indicate that the perception of interdisciplinarity varies thereby influencing programme design. Communication and collaboration skills are important interdisciplinary skills. Assessment of these skills seem in its infancy. We may conclude that interdisciplinarity seems only occasionally to be a systemic endeavour due to different interpretations of interdisciplinary education itself and subsequently the knowledge of how to design interdisciplinary education.