Section 3 of the text, the longest, contains 14 chapters overviewing less common genetically based disorders that are seen in academic and general practice settings. Examination of these relatively less common disorders is instructive regarding the relationships between genetics and behavior. Syndromes covered in this section include Turner’s, Tourette’s, fragile X, Noonan’s, phenylketonuria, Rett’s, Prader-Willi, Klinefelter’s, Down’s, neurofibromatosis, and seizure disorders, among others. This section is particularly valuable for the updated information the chapters provide on genetic advances in the diagnosis and neurobiology of these disorders. Sensitive, detailed, and highly illustrative case vignettes are presented outlining the convergence of genetics and the neuropsychological and neurobehavioral phenotypes of the disorders. Clinicians who strive to understand the connection between genetics, brain function, and brain structure on the one hand and behavioral/psychological phenomena on the other will find these chapters highly satisfying and thought provoking. The chapters in section 3 are well referenced, and many include contacts, addresses, web sites, and online support/news groups for the respective syndromes. This is particularly useful for clinicians seeking to keep abreast of new developments and for providing information to parents and families.