The Bologna reform has transformed higher education in Europe leading to more flexibility but also complexity in the structure of study programs. As study planning becomes more challenging for students, supporting this process becomes more relevant in research. This paper’s main contribution is an in-depth exploration of the factors which influence students’ course selection and how they might be addressed by a digital study planning assistant or related systems. To gain insights on how exactly students select their courses, previously collected interviews were reanalyzed, personas of typical student behaviour were extracted and further social aspects of planning were conducted via a group interview. For course selection, 14 aspects and three personas representing different types of selection behaviour were extracted from the interviews. For the group interview, several social factors on the group, community and external level that are related to students’ study planning decisions were collected. Emerging ideas regarding the realization of these factors in a supporting system are presented and may be valuable to similar projects.