The Dutch government has set the policy goal of integrating a broad range of ambulatory and in-patient mental health services. The current Dutch system is comprised of autonomously functioning in-patient and out-patient services. In Rotterdam both the in-patient and out-patient sectors are undergoing change and have begun to integrate their services on a city-wide basis. This paper compares the Rotterdam experience with the community mental health services in the United States. From these data organizational criteria and necessary conditions for the adequate functioning of a broad range of mental health services is drawn. These include a clear division of functioning and tasks, limiting the obstruction to patient flow between services, the decentralization and 'unitizing' of services in which 'liaison' personnel are staffed, based on the referral frequency between services.