Aims. To explore the practice of cooperation in mental health care across services and identify conditions that promote and inhibit cooperation.Methods. Focus groups with relevant service providers were conducted in four exemplary regions in Germany (rural/ urban and East/West). The discussions were content analysed.Results. Seven central categories were deduced: (1) involved service providers, (2) comprehension, (3) reasons, (4) instruments for cooperation, (5) promoting and inhibiting conditions, (6) interdisciplinarity, and (7) regional and personal networks. Cooperation is practiced in networks, rather than defined relations. Who is involved in cooperation depends on patients/clients needs and may vary from case to case. Service providers do not have theoretical concepts of cooperation. Cooperation relies not only on personal contacts and knowledge between services but also on time, financial reimbursement and the social capital of the environment. In particular, cooperation with physicians was considered to be difficult by non-medical professionals. Physician's role models do not seem to include cooperation with other disciplines as a core task.Conclusions. To improve cooperation, regional and sustainable mental health networks have to be systematically implemented by providing leadership, time and reimbursement for network meetings. Interdisciplinary cooperation practice should be part of the curricula of medical students and residents in psychiatry.