Pre-school teacher education in Norway is organised in knowledge areas, which are often denoted as interdisciplinary, consisting of several disciplines. However, interdisciplinary teaching and interdisciplinary research are ambiguous concepts, and can refer to various goals and characteristics. In this paper, we discuss concepts related to interdisciplinarity and sketch associated requirements and challenges. We further investigate whether regulations demand certain forms of interdisciplinarity. Based on literature on interdisciplinary research and interdisciplinary education, we divide the concept into transdisciplinary, interdisciplinary and multidisciplinary, and we suggest what these may represent in research and education.