Research on the factors affecting progress in medical schools has typically focused on mainstream (non-Indigenous Australian, non-international) students in traditional, didactic programmes. These results may not be applicable to students, particularly those from culturally diverse backgrounds, undertaking problem-based learning courses. Objective This study used qualitative methodology to explore and compare factors affecting progress for mainstream Australian students (non-Indigenous Australian, non-international) and international students (full fee-paying students who had relocated countries to study) in a problem-based learning medical course. Intervention strategies were devised on the basis of the participants’ experiences. Methods Six focus group discussions were conducted (three with mainstream Australian and three with international participants). Transcripts of these discussions were coded and analysed independently by two researchers and discussed until consensus was attained. Results Participants identified both positive and negative experiences related to the course structure, which were consistent with previous findings. The participants’ experiences demonstrated a relationship between sense of ‘belongingness’ to the medical school community, participation in learning opportunities and progress through the course. Conclusions The results suggest that interventions aimed at reducing barriers to progress need to promote students’ confidence, motivation and subsequent participation in course learning opportunities. These results have application to other problem-based learning courses particularly those which face the challenge of providing an optimal learning environment for students from diverse backgrounds.