Context Rather than merely acting professionally, medical students are expected to become professionals. Developing an embodied professional persona is not straightforward as there is no single perspective of what medical professionalism comprises. In the context of this confusion, medical educationalists have been charged with developing a professionalism curriculum that emphasises, supports and measures students' professionalism. This paper focuses on medical students' discourses of medical professionalism in order to understand the means through which students conceptualise professionalism. Methods Discourse analysis was undertaken. Two hundred students from three medical schools (in England, Australia and Wales) participated in 32 group and 22 individual interviews. Students' explicit definitions of professionalism were inductively coded according to the dimensions of professionalism they identified (n=19) and the discourses of professionalism they used (individual, collective, interpersonal, complexity). Connections were explored between pre-clinical and clinical students' understandings of professionalism across the schools and the respective policies, documents and teaching opportunities available to them. Results Understandings of professionalism differed between pre-clinical and clinical students and between schools with different approaches to professionalism education. Students who experienced early patient interaction and opportunities to engage in conversations about professionalism within clinician-led small groups demonstrated complex, embodied understandings of professionalism, drawing on all four discourses. Students who learned predominately through lectures used a restricted range of discourses and focused on dressing or acting like a professional. Conclusions Providing students with opportunities to engage in active sense-making activities within the formal professional curriculum can encourage an embodied and sophisticated understanding of professionalism.