Education for sustainable development creates new challenges for universities where faculty and staff are expected to prepare students to meet complexities in society and take responsibility for sustainability, which scientists are urgently calling for today. Few studies exist on how faculty and staff perceive sustainability in their functions at the university based on long-term sustainability implementation and training within a 14001 certified environmental management system. This university case study with data collected by open-ended survey questions explores how faculty and staff express their role in sustainability work within a Swedish university.The authors developed a model to illustrate development of sustainability competence and its institutionalization. Results show a large variation in perceptions of sustainability from waste separation to a complex understanding and integration of issues into education. Integration of sustainable development as a university core competence is difficult for a whole university to reach. Interpretational flexibility provides opportunities for discussing the sustainability concept in diverse academic traditions in different disciplines. Top management inspiration on different university levels is essential for integration. Continuous training and routines contribute to movement towards institutionalization of sustainability activities and to following up the process in universities.