A range of stakeholder groups are involved with fostering Education for Sustainable Development (ESD). It is crucial that their views on the aims of ESD are aligned. This is a prerequisite for coordinated integration of ESD into the formal education system. However, research has not explored whether stakeholder groups have similar ideas about the aims and learning outcomes of ESD. This study investigates the differences and similarities in stakeholders' opinions on the sustainability key competencies students should develop. We conducted 15 interviews with German experts in ESD practice, policy, and science, analyzing the results deductively using Qualitative Content Analysis within the UNESCO framework of Key Competencies for Sustainability. An inductive approach was used to identify aspects and concepts of competence that went beyond this framework. Most of the competencies mentioned could be assigned to the UNESCO framework, but we identified the additional competency of participating at the political level as being important for ESD. The experts also identified several other concepts. The three stakeholder groups emphasized different competencies and concepts, probably due to their differing professional backgrounds. However, similarities predominated, and the experts largely agreed on which competencies should be developed. Structural difficulties with integrating ESD into the education system are therefore not likely to be the result of fundamental differences in perspective between the three stakeholder groups on the aims of ESD. However, their different frames of reference might lead to miscommunication and misunderstanding, which could impede integration. This aspect needs thorough examination in the future.