This paper presents first results of a research project aimed at improving co-operative work initiatives in hospitals. A holistic analysis of the treatment process is presented as a precondition for process reengineering, quality measurements and improvement of multi-professional co-operation. Treatment process modelling attempts within the last years have concentrated on specialised points of views, such as business process modelling or communication modelling. In contrast, we have developed a framework consisting of several views of the treatment process. We tested our framework in a broad system analysis within the Department of Child and Adolescent Psychiatry of the Heidelberg University Hospitals. Our preliminary results support the framework. Weaknesses were described precisely in both the field of organisational procedures and information management.