In this up-to-date survey and critical assessment of transgenic and knockout models in neuropsychiatry and behavior, a panel of leading researchers comprehensively assesses how and whether the genetic abnormalities produced from these models manifest the neuropsychiatric disorders to which they correspond. The authors focus on transgenic and knockout models of neurocognitive dysfunction and neuropsychiatric dysfunction. The discussion of neurobiological problems covers mental retardation, polyglutamate, and speech disorders, as well as disorders that involve cognitive, social, speech, and language dysfunction.