The supervision of degree theses is one of several institutional practices in higher education that are regulated by various systems of rules. However, the social roles involved in the practices may still be largely based on interpretation, negotiation and personal choice. Research on supervision has primarily targeted the doctoral level, but the present study targets the Bachelor level. Existing inventories of roles are based on supervisor roles, but the present study also includes student roles. Existing inventories are not always based on empirical data, but the present study uses focus group discussions with supervisors and responses to open-ended questions from a questionnaire to students as a basis for extracting supervisor and student roles. The supervisor and student participants came from two language departments at a Swedish university. The local guidelines relevant to supervision underspecify roles. The findings show a considerable complexity and a broad repertoire when it comes to roles attributed to supervisors as well as students. Some roles may be plotted along a scale, where stakeholders may have different preferences and needs, such as along transactional and interactional types, or between support and management; or between seeing the thesis primarily as a process or a product.