This summary provides an overview of the assessment, differential diagnosis, and treatment recommendations contained in the Practice Parameters for the Assessment and Treatment of Children and Adolescents With Obsessive-Compulsive Disorder. OCD is a disorder of heterogeneous origin characterized by intrusive thoughts or compulsive urges or behaviors that are distressing, time-consuming, or functionally impairing. In children and adolescents, the disorder often is accompanied by a wide range of comorbidity. Two modalities have been systematically assessed and empirically shown to ameliorate the core symptoms of OCD: cognitive-behavioral therapy (primarily exposure/response prevention) and serotonin reuptake inhibitor medication. Additional individual and family psychotherapeutic, pharmacological, and educational interventions often are necessary. J. Am. Acad. Child Adolesc. Psychiatry, 1998, 37(10):1110–1116.