Objective-The purpose of the study was to examine adaptive, emotional, and family functioning in a well-characterized group of children and adolescents with obsessive-compulsive disorder (OCD) and to evaluate the influence of comorbid attention deficit hyperactivity disorder (ADHD) on the levels of impairment in various functional domains.Method-The study group included 287 children and adolescents (191 boys, 96 girls) ages 7-18 years. Fifty-six subjects had a diagnosis of OCD only, 43 had both OCD and ADHD, 95 had ADHD, and 93 were unaffected comparison children. Best estimate DSM-IV diagnoses were assigned on the basis of structured interviews and clinical ratings. The children's functioning was evaluated with a comprehensive battery of well-established, standardized measures, including the Vineland Adaptive Behavior Scales, parents' ratings of social and family functioning, and children's self-reports of emotional adjustment.Results-The children with OCD only were more impaired than were unaffected comparison subjects in most areas of adaptive functioning and emotional adjustment. Children with OCD plus ADHD had additional difficulties in social functioning, school problems, and self-reported depression. Impairment in daily living skills, reduced number of activities, and self-reported anxiety were uniquely associated with the diagnosis of OCD. Family dysfunction was associated with ADHD but not with OCD.Conclusions-Children and adolescents with OCD are impaired in multiple domains of adaptive and emotional functioning. When comorbid ADHD is present, there is an additional burden on social, school, and family functioning.Obsessive-compulsive disorder (OCD) is a neuropsychiatric condition characterized by distressing and intrusive thoughts, impulses, or images (obsessions) and repetitive overt or covert behaviors (compulsions) performed to reduce distress. A diagnosis of OCD requires that the symptoms cause marked distress or significantly interfere with the person's functioning. OCD is present in 2%-4% of adolescents (1,2), although it is probably less common in prepubescent children (3). In groups of OCD subjects drawn from clinical settings, the lifetime rates of comorbidity with depression, anxiety, and tic disorders have been estimated to be as high as 80%, 70%, and 60%, respectively (4-7). Clinical accounts often reflect that children with OCD are impaired in their daily routine, emotional adjustment, family and peer relationships, and academic performance. Although many reports of the phenomenology and clinical features of childhood OCD are available, many studies have failed to use standardized measures of adaptive functioning, and they have been limited by small size of the study groups and the absence of comparison groups (8-13).Comorbidity with attention deficit hyperactivity disorder (ADHD), a common childhood psychiatric disorder, has been relatively neglected in the research on childhood OCD. In reports on groups of subjects in clinical settings, the rate of co-occurrence of the two con...