The Ruhr area looks back over a long history of migration and cultural diversity. People from many different cultures and social milieus live in the cities of the Ruhr area. That being said, discourses have emerged in contemporary society about the recognition of cultural difference and the opportunities and problems of co-existence under multi-cultural conditions. Modern cities and those responsible for them attempt to understand the complexity of these conditions by commissioning scientific expertise in order to manage cooperation among the heterogeneous cultures and to enter into a communicative relationship with local residents. It is against this background that researchers at the Institute for Communication Studies at the University of Duisburg-Essen have investigated how the city Mülheim/Ruhr can represent itself to local residents, both with and without a migration background, as cosmopolitan and tolerant, and how the city’s communication with its residents enables Mülheim to be perceived as a “city for all residents”. In the process, surprising insights arose concerning the assumptions of municipal authorities and the actual perceptions of Mülheim residents about the reality of life in the city.