This book covers the whole spectrum of delusional syndromes, which may be presented either as autonomous disorders or as symptoms of other major psychotic disorders. Some of them are rather common and can be seen by every clinician in various nations and cultures. Others are rare or culture-related with higher prevalence in some cultures and lower in some others. Exact clinical descriptions of the syndromes are accompanied by a detailed picture of their longitudinal course and prognosis. Numerous studies on and approaches to therapy are presented and practical recommendations are given. This book not only discusses the results of modern scientific work but also goes back to the roots and provides valuable information from the original historical literature from English as well as German and French speaking countries. It abandons some myths on this topic and illustrates the clinical reality of this fascinating group of psychiatric disorders.