Problem-based learning (PBL) is a learner-centred approach “that empowers learners to conduct research, integrate theory and practice, and apply knowledge and skills to develop a viable solution to a defined problem” (Savery, 2006, p. 12). Thus, the PBL classes differ pedagogically from traditional teacher-led classes. This learner-centred pedagogy, which was originally developed in medical education at a Canadian university in the late 1960s, was first incorporated into a tertiary-level curriculum in Japan in 1990. Since its initiation, 75 Japanese medical schools (94%) have adopted the PBL approach in their curriculum. Notwithstanding the great interest in using PBL in Japanese medical education, there is little qualitative research on the cultural dimensions of students’ participation in PBL tutorials. This study explored these issues by providing a close examination of classroom discourse and students’ introspection on their learning in PBL tutorials. In this qualitative case study, nine focal students and 36 of their group members, all of whom were first-year undergraduate students at a Japanese university, were selected as the main research participants. Data were collected over an entire academic year through classroom observations, video-recordings of PBL tutorials and interviews. Analysis of the classroom interactions involved the application of classroom discourse analysis (Eggins & Slade, 1997; Sinclair & Coulthard, 1975; Tsui, 1994). Moreover, interview data were analyzed by following a Grounded Theory approach (Strauss & Corbin, 1998) to provide further insights into their changing thoughts during their ongoing participation. Grounded in the notion of community of practice (Lave & Wenger, 1991; Wenger, 1998), this study examined the cultural dimensions of Japanese students’ participation in PBL tutorials. In particular, it focused on gaining a better understanding of what they actually do in the discussions, identifying factors mediating their participation and examining the relationships between their actual engagement and thoughts in the tutorials. In this study, there was considerable variation amongst the Japanese students in the ways they participated in and responded to PBL practices. Furthermore, this study demonstrated that their participation was mediated by their cultural assumptions, recognition of competence, negotiation of power relations and identity formation as a group member in the social context of PBL tutorials. Therefore, Japanese students cannot simply be categorized into quiet, passive and dependent learners. Rather, their ongoing participation in PBL tutorials is situated in the specific cultural context. The findings suggest that exploring the cultural dimensions of students’ participation and negotiation of identities, power relations and competence provides a broad view of their learning, including their ways of knowing, doing and being a member in a context of student-centered classroom. This study concluded that the inquiry into Japanese students’ participation contributed to our understanding of the processes of students’ learning and the social and cultural factors mediating their participation in a new classroom community. In particular, the mere adoption of a certain approach of learning will not bring about positive learning outcomes. It should be noted that students’ participation in a new classroom context involves complex, dynamic, social and cultural processes. / published_or_final_version / Education / Doctoral / Doctor of Philosophy