The role of workplace supervisors in the clinical education of medical students is currently under debate. However, few studies have addressed how supervisors conceptualize workplace learning and how conceptions relate to current sociocultural workplace learning theory. We explored physician conceptions of: (a) medical student learning in the clinical workplace and (b) how they contribute to student learning. The methodology included a combination of a qualitative, inductive (conventional) and deductive (directed) content analysis approach. The study triangulated two types of interview data from 4 focus group interviews and 34 individual interviews. A total of 55 physicians participated. Three overarching themes emerged from the data: "learning as membership," "learning as partnership" and "learning as ownership." The themes described how physician conceptions of learning and supervision were guided by the notions of learning-as-participation and learning-as-acquisition. The clinical workplace was either conceptualized as a context in which student learning is based on a learning curriculum, continuity of participation and partnerships with supervisors, or as a temporary source of knowledge within a teaching curriculum. The process of learning was shaped through the reciprocity between different factors in the workplace context and the agency of students and supervising physicians. A systems-thinking approach merged with the "co-participation" conceptual framework advocated by Billet proved to be useful for analyzing variations in conceptions. The findings suggest that mapping workplace supervisor conceptions of learning can be a valuable starting point for medical schools and educational developers working with changes in clinical educational and faculty development practices.