BACKGROUND Writing a bachelor thesis has a central role in nursing education. Nursing students require both information and academic literacy in order to write their theses, and there is an expectation that these skills will contribute to putting their knowledge into practice. OBJECTIVE To describe students' perceptions of the student and supervisor roles and to investigate students' experienced self-efficacy during the supervision of their bachelor thesis. METHODS A cross-sectional pre-post design. METHODS Four universities were included. All four had bachelor thesis courses organized as a group supervision process, with a student active approach. Nursing students met together one hour prior to meeting with their supervisor, in order to discuss concerns, try to solve upcoming problems, and plan the agenda for the upcoming supervision session. METHODS A total of 472 undergraduate nursing students were invited to participate. METHODS A web-based questionnaire was used, incorporating the Supervision of Thesis Questionnaire and the General Self-Efficacy Scale. Data were collected at two points: before and after the thesis course. Descriptive statistics and frequencies were calculated, and the independent t-test and Mann-Whitney U test were used for analytic analysis. RESULTS The response rate was 39 % (160/472) pre-course and 28 % (130/472) post-course. Nursing students had high expectations of supervision at both time points. Students reporting high self-efficacy had higher expectations of the supervisor's knowledge of the subject and the methods, compared to those reporting lower self-efficacy. CONCLUSIONS Nursing students reported high expectations for the supervision process, the supervisor, and themselves, both when entering and when ending the bachelor thesis course. Self-efficacy may contribute to these expectations. Active learning in a group (i.e., collaborative learning) may contribute to nursing students' commitment during the group supervision process in a bachelor thesis course. Further studies are warranted on the optimal group composition to support learning during bachelor thesis courses.