The focus of this study was to explore doctoral supervisors' perceptions of the factors contributing to doctoral studies. The study draws on the job demands-resources (JD-R) framework to analyze supervisors' perceptions of core resources and challenges at different levels of doctoral education. The data comprise 15 semi-structured interviews with professors in their roles as supervisors in economics, medicine, natural sciences, engineering, humanities and social sciences at three Finnish universities. The supervisors identified a variety of resources and challenges related to structures, organization of doctoral studies, the scholarly community, supervisory relationships, and individual competence. Slightly more challenges than resources were identified. The challenges described were related to structural elements and embedded in the research community, whereas many of the perceived resources were associated with social aspects of work. The results highlighted the importance of different supervisory resources such as a good supervisor-student relationship, support of the research team, and international contacts, as ingredients of high-quality supervision in the doctoral process. The study also showed that many of the challenges require focusing on and developing the whole community rather than individuals.