Positioning Dynamics: Dealing with power and perspectives in collaborative decision-making on preventive care In healthcare, something magical is often expected from collaborative decision-making: collaboration could enable us to bridge different power positions and perspectives and make decisions on an equal footing. Yet, decision-making is often hindered by problems during collaborative processes. How does that magic of collaboration work? I investigate this in my dissertation by exploring how collaborative decision-making on preventive care takes place between patients, healthcare professionals and representatives of healthcare organisations. My qualitative research shows how these different actors each develop a position during the decision-making process. Their position is not only determined by their own knowledge and interests, but also by how they anticipate other(s). By anticipating each other, a positioning dynamic is created that determines how collaborative decision-making on preventive care proceeds. An important insight is that positioning dynamics are not rational-strategic, nor problem-oriented: positioning is a mundane and relational process, and therefore embedded in existing power relations and experienced as meaningful by the patients, professionals and organisation representatives involved. It shows that collaborative decision-making does not magically resolve differences in power and perspectives, but can help to better deal with power relations and different perspectives.