This article focuses on the question what the parameters are for the treatment of personality disorders. In other words: what are the considerations in the process of assessment for treatment and which treatment approach is indicated. Developments with regard to the treatment of personality disorders from two therapeutic methods will be described: The cognitive-behavioral therapy and the psychoanalytic psychotherapy. Based on theoretical concepts and clinical experience keymoments in the treatment in which one intervenes on a symptomatologic level or on the level of the structure of the personality are discussed. Some rather difficult differential diagnostic fields in clinical practice are discussed, as well as the meaning of contact during the assessement process. Modalities in the treatment are reviewed. The conclusion of this article is that assessment and treatment of personality disorders requires expertise in biological, psychological/ psychodynamic and social/interactional aspects of the pathology. The necessity to combine various methods of treatment and to integrate approaches creates a design for 'psychiatric psychotherapy'.