21 General introduction participants can be informed about ethics in general and MCD in particular, and they learned more about morality, dialogue, and moral dilemma. Another lesson from the pilot was that staff often mentioned they felt little connection to the discussed dilemma since it did not play a role in their practice. MCD sessions were multidisciplinary, and group composition would change every session during the pilot. Interviews showed how staff felt the need to first experience MCD with their team, and a multidisciplinary group would potentially be appreciated at a later moment in the process. The staff also mentioned they would be more willing to open up about their considerations and thoughts if the MCD sessions did not have so many participants they did not work with on a daily basis. Another lesson we learned is to better instruct the MCD facilitators to create enough room during MCD for the last steps of the conversation method, in which participants jointly reflect on how to transfer the insights to practice. Based on the unfamiliarity with MCD, many sessions seemed to not have enough time left for these important last steps during MCD. Furthermore, we learned that during the start of an MCD session the facilitators need to help staff translate their (organizational) struggles into the formulation of the related moral dilemmas, which could then be discussed during MCD. We also learned that for prison staff to open up more, it would be best to not always include the team manager in the MCD session, unless a team explicitly requests it. Another lesson we learned was about the vocabulary used by prison staff and we used these insights to better instruct MCD facilitators. For example, we constructed a list of typical DCIA abbreviations for the MCD facilitators. Prison staff initially stated they never experienced doubts in practice, so reflections on situations of doubt would be unnecessary. When we eliminated the word doubt and asked them about their challenging experiences from practice, a dilemma would come forward more organically. We also learned from a lack of regulations concerning the planning and implementation of MCD. We noticed some staff members had never experienced MCD; by contrast, others in the pilot participated more than ten times. Additionally, the composition of the multidisciplinary groups and their facilitators differed each session. A more structured and regulated approach seemed to be best for all involved; to create calmer conditions for fruitful MCD sessions and a preset number of sessions more suitable for our research. These lessons from this pilot helped us to shape the research design and the implementation and organization of the MCD sessions in the DCIA locations of the main study. 1