This book provides a comprehensive update on multiple aspects of the wide-ranging topic of mental retardation. The opening part of the volume is dedicated to the definition of mental retardation and to the various classification systems, within an epidemiologic perspective. A second core section presents the neuropsychology of mental retardation, considering both the global approach to the identification of the different deficits present in this condition, and the definition of specific cognitive-behavioural phenotypes possibly related to distinct genetic syndromes or gene defects. Of particular interest are some contributions to the neurological diagnosis of mental retardation, providing the clinical description of several specific disorders and genetic syndromes, and outlining the essential diagnostic input provided by genetic tests. The psychiatric comorbidity of mentally retarded subjects is presented, and specific chapters are geared to the medical treatment of mental retardation and the psychopharmacology of the associated neuropsychiatric disorders. A final section deals with several cognitive, psycho-pedagogic, and psycho-educative rehabilitation approaches focusing on the life-long disability deriving from mental retardation.