{"p"=>"Youth mental disorders are prevalent and show homotypic and heterotypic continuity. We followed a community sample of 609 families with 3-year-old children living within 20 contiguous miles of Stony Brook, NY, with at least one biological parent; primary caregivers were required to speak English, and children with significant medical or developmental disorders were excluded. Participants were assessed at three-year intervals from ages 3–18, tracking the prevalence and continuity of five common mental disorders (depression, anxiety, attention-deficit/hyperactivity disorder, disruptive behavior, and substance use disorders) via semi-structured diagnostic interviews. By age 18, estimated cumulative prevalence rates were: depression (34.7%), anxiety (55.9%), disruptive behavior disorders (DBD; 19.4%), attention deficit hyperactivity disorder (ADHD; 22.6%), and substance use disorders (SUD; 11.9%). Depression prevalence rose with age; anxiety remained consistently high; DBD declined after age 6; ADHD peaked at age 12; and SUD sharply increased at age 18. The cumulative prevalence of any mental disorder by age 18 was 71.8%. We found substantial homotypic and heterotypic continuity. The latter was greater within than between the internalizing and externalizing domains. Early psychopathology (< age 6) significantly increased later disorder risk. These data highlight the substantial burden and developmental course of common youth mental disorders from preschool through late adolescence."}