The development of the International Classification of Diseases has been a major step in the development of a common understanding of mental disorders. But classification by symptoms limits professional communication especially when we want to focus on functional problems caused by persisting mental health conditions. “Functioning? concerns all areas of life of affected persons and represents that side of their illness which interests patients mostly. Before this background an additional classification system has been developed aside from the International Classification of Diseases. The International Classification of Health and Functioning describes not only the deficits of disabled persons but also their resources. As such this classification system is not just an add-on to another classification system but it also expresses a new treatment approach directed toward recovery and remission. It also involves affected persons in their rehabilitation und treatment and indicates a new relationship between patients and professionals.