In this study, a group of students were interviewed longitudinally during their first year in physics at a university Denmark, and another group of students were interviewed after they had decided to leave physics at a university in Sweden. The interviews were designed to allow access to the students’ reflections about staying and leaving relative their perceptions of cultural and structural conditions for learning in the respective programmes. The design were based on the idea that retention and attrition is a process: during their studies, students adapt to the programme, content and teaching activities as a consequence of the intended and maybe unintended learning that takes place. Analysis of these interviews yielded a set of qualitatively different categories for understanding students’ reasoning on their interactions in the programme. One category is instrumentalisation of teaching-learning situations, another is internalization of challenges to participation and a third is renegotiation of pedagogical discourse (i.e. the curriculum). It turns out that these categories can be used to characterize and understand students’ processes of developing and sustaining a sense of belonging over time, or alternatively to understand their decision for leaving – relative cultural and structural conditions for learning in the programme.