This book was developed to be a practical summary of some of the common syndromes related to developmental disability for professionals and students in the field. The editors have selected some common and some lesser known syndromes that are associated with persons with developmental disabilities and coexisting mental or behavioral challenges, specifically Fragile X, Down, Williams, Smith-Magenis, Pervasive Developmental Disorders, Tourette's, 22q Deletion, Smith-Lemli-Opitz, and Angelman Syndrome. The objective was to demonstrate how and why support and treatment can be individualized by recognizing the differential realities of persons, with various syndromes, who are all labeled as developmentally disabled.