The clinical presentation of OCD in children and adolescents is quite similar to that in adults, with overlapping obsessional content and compulsive ritualistic patterns. In addition, both age groups provide essentially identical descriptions of the anxiety accompanying their compulsions and invoke similar mechanisms to resist acting out the ritualistic behavior. Responses to behavioral treatment and pharmacotherapy are similar across ages, and the disorder appears to be chronic and unremitting in the studied populations whether its onset is in childhood or adulthood. Conversely, the strong familial influence, male predominance, neuroendocrine abnormalities, presence of tics and other neurologic abnormalities, and possible impact on personality development suggest that pediatric OCD has important differences from its adult counterpart. Further investigations of these unique features of childhood-onset OCD are warranted and may provide etiologic clues to the disorder.