Chronic depersonalisation-derealisation syndrome is still considered a difficult disorder to treat, although it is not a rare mental illness. Professionals also lack well-prepared information about the disorder and adequate therapeutic methods. In the guide, psychotherapists will find detailed information on the symptoms and diagnosis of the disorder as well as concrete approaches for psychotherapeutic treatment and psychoeducation. The theoretical content is impressively illustrated by the many patient examples described in detail. In the appendix and as electronic supplementary material, 14 worksheets are included which have been tested for practical use in therapy.