Tourette's syndrome (TS) is associated with several clinical features, including tics and behavioral disturbances (e.g., obsessive compulsive, attention deficit hyperactivity disorders), that might impair school performance. The spectrum of the TS behavioral disorders, however, remains unclearly delineated and controversial. Since recent evidence indicates that TS and related tic disorders are much more common than generally appreciated, we hypothesize that TS is an important contributor to academic failure in the childhood population at-large. This notion is important since TS is treatable and institution of appropriate therapy could favorably impact on school performance. We now propose a community-based epidemiological survey, involving direct interviews, for the prevalence of tic disorders in a randomly selected sample of 1500 special education and 3000 matched control regular classroom students in Monroe County. (Rochester), NY. Secondly, we will utilize a structured clinical interview (DISC) and parent and teacher self-reporting instruments to compare students in both the special education and regular classroom populations with or without tics for the prevalence of behavioral (disruptive behavior, anxiety, mood, adjustment, we will include only those school districts (Rochester City, 7 suburban districts) where students in regular classroom and special education programs are fully integrated within the same schools. This study will: 1) provide definitive information regarding the true prevalence of TS, 2) determine whether children requiring special education represent a high-risk group for the disorder, and 3) clarify the true boundaries of the TS behavioral disorder. The possibility that TS, a hereditary and potentially treatable disorder, is responsible for a substantial fraction of school problems in the childhood population at- large might have profound medical and educational implications. Accurate delineation of the TS behavioral spectrum should allow a more precise definition of the disease phenotype and importantly contribute to the success of genetic linkage and other approaches aimed at elucidating the neurobiologic mechanisms of the disorder.