At present there is a paucity of standardised group behaviour therapy approaches targeting different kinds of personality disorders. On this background, our research group developed a new manualised treatment approach ("Schema-focused Emotive Behavioral Therapy"; SET), which integrates schematherapeutic, emotion-focused, cognitive and behavioural therapy methods. A multi-centre RCT-study evaluated SET based on a sample of 93 patients with personality disorders of clusters B and C. This study compared SET (n=47) with a classical Social Skills Training (SST, n=46) over 30 sessions. Patients were assessed before and after treatment and one year after study intake (follow-up). SET showed significantly higher improvements in several domains such as interpersonal behaviour, emotional coping, and symptomatic impairments. Clinically relevant effects on the SET occurred both in a reduction of the suffering from the disorder, severeness of the disorder, and hope for improvement. Furthermore, SET obtained a highly significant reduction of the dropout rate and a significantly increased use of therapy. Similar results for both comparison groups were found regarding behavioural coping and self-effectiveness. Results indicate that SET both entails a high acceptance of treatment and offers an adequate and effective group therapy for patients with personality disorders. From a clinical and economic point of view, SET promises to significantly contribute to mental health care.