Research universities are increasingly incorporating interdisciplinary education into their strategies. In this transition from monodisciplinary to interdisciplinary education, there is a need for insight into the optimal implementation of such activities. The current study investigates university lecturers' interpretations of interdisciplinary education, their approaches towards developing interdisciplinary modules, and the challenges they face in teaching these. Based on interviews with nine lecturers, three interpretations of interdisciplinarity emerged. From the first interpretation, lecturers teach monodisciplinary knowledge and skills and expect the students to collect different perspectives. A second interpretation emphasises participating students as being disciplinary experts that share their knowledge throughout the module. The third interpretation takes the theme of the module as a starting point for interdisciplinarity. Regardless of their interpretation, lecturers face challenges in addressing prior knowledge, student interests, fostering student collaboration and maintaining consistency. Based on these findings, we offer suggestions for future SoTL research and advocate for a stronger emphasis on professionalisation activities.