Psychotherapy in psychotic disorders is a rare condition and is confronted with much scepticism. On the background of intensive research - in particular in Great Britain, sufficient empirical evidence is available from randomised clinical trials to recommend Cognitive Behavioural Treatment for routine care. However, many research questions are open. In particular, the specific efficacy compared to supportive treatment is unclear and the mechanisms of action as well as economical aspects should be investigated more intensively. The psychotherapy research network "psychotherapy of psychotic syndromes" conducts research projects on these issues. The present paper gives an overview over the treatment and the scientific concept of this network.