This paper draws on an extensive literature review about students’ integration into higher education and the reasons why some students decide to leave their study programme before completing. Results show that there are no simple explanations as to why some students drop out of their studies and other students decide to stay. Previous studies have tended to focus on deficits within the students as reasons for dropping out, particularly insufficient prior knowledge. Although students’ preparation influences their persistence, students’ academic level and abilities alone cannot explain why some students persist and others opt out. To understand the complexity of the problem the review highlights the interaction of three explanations: 1. The learning environment as well as the design of the curriculum. 2. The integration of the students into the cultural context of the study programme, and their identity-work in terms of gaining a sense of belonging and becoming a legitimate member of the group of ‘science people’. 3. How the student’s social, economic, and cultural background (or habitus) influence the process of integration and student persistence.