Background: Student-run clinics (SRCs) are outpatient clinics run and organized by undergraduate medical students. While these clinics offer participating students multiple learning opportunities, little is known about how participation in an SRC contributes to learning and how this learning is influenced. Methods: In this qualitative clarification study, we conducted semi-structured interviews with a purposive sample of 20 students and student-coordinators participating in our learner-centred SRC (LC-SRC), to gain in-depth insight into their experiences and learning. These interviews were analysed using Glaser's approach to grounded theory. Results: Analysis revealed that responsibility, authenticity, and collaboration described how SRC participation contribute to learning. Responsibility encompassed the responsibility students had for their patients and the responsibility that the student coordinators had for the students. Authenticity reflected the context and tasks in the LC-SRC. Collaboration covered collaboration with other students, with student coordinators, and with clinical supervisors. These three themes are interrelated, and together enhanced motivation and promoted patient-centred learning in both the LC-SRC and the regular curriculum. Conclusions: Learning in an LC-SRC is highly dependent on students' feelings of responsibility for real authentic tasks and is stimulated by extensive collaboration with fellow students and supervising doctors.