Background: Interprofessional education in the healthcare sector is becoming increasingly recognised in Germany and is increasingly being included in the curriculum. The learners are usually the focus of research. This study focusses on the teachers, as they are the ones who carry out the teaching and thus prepare the learners for practice. This article focuses on the perception of competence boundaries and the assumption of responsibility in an interprofessional setting. Methods: Using a mixed methods design, interprofessional courses were first identified across Germany in relation to the three professions of medicine, nursing and physiotherapy. Based on 76 fully completed quantitative questionnaires, the respondents' views were surveyed with regard to the competences of the teachers, among other things. In 15 interviews, experts were asked more in-depth questions about competence limits and the assumption of responsibility, whereby the data material was analysed according to Kuckartz's structuring qualitative content analysis. Results: Recognising profession-specific boundaries is considered important by 70% of respondents, but only 43% of respondents consider it important to take joint responsibility. The interviews show that legal framework conditions are crucial, but so is adherence to established roles and habits. Conclusion: (Self-)reflection is required in order to develop a shared assumption of responsibility. The actors must orientate their joint actions towards the needs of the patients and think across professions. As the process of (self-)reflection rarely takes place in mono-professional training programmes, opportunities to learn it are needed.