The evidence-based guideline provides recommendations for the diagnosis and psychotherapy of schizophrenia and other psychotic disorders such as delusional disorders and schizoaffective disorders. The treatment guideline was developed by an expert team from the Clinical Psychology and Psychotherapy division of the German Psychological Society. It is based on the current knowledge regarding effective psychotherapeutic interventions for psychotic disorders. The volume offers a concise description of the disorders, provides recommendations for diagnosis and differential diagnosis, and presents possible risk factors and etiological models. The current evidence for various psychotherapeutic approaches is presented, taking into account the improvement of different symptom areas, relapse rates, and psychosocial functioning levels.