Although rhetoric abounds about the importance of patient-, person- and relationship-centered approaches to health care, little is known about how to address the problem of dehumanization through medical and health professions education. One promising but under-theorized strategy is to co-produce education in collaboration with health service users. To this end, we co-produced a longitudinal course in psychiatry that paired people with lived experience of mental health challenges as advisors to fourth-year psychiatry residents at the University of Toronto. The goal of this study was to examine this novel, relationship-based course in order to understand co-produced health professions education more broadly. Using qualitative interviews with residents and advisors after the first iteration of the course, we explored how participants made meaning of the course and of what learning, if any, occurred, for whom and how. We found that the anthropological theory of liminality allowed us to understand participants' complex experiences and illuminated how this type of pedagogy may work to achieve its effects. Liminality also helped us understand why some participants resisted the course, and how we could more carefully think about co-produced, humanistic education and transformative learning.