The National Comorbidity Survey Replication Adolescent Supplement (NCS-A) was designed to estimate the lifetime-to-date and current prevalence, age-of-onset distributions, course, and comorbidity of DSM-IV disorders in the child and adolescent years of life among adolescents in the United States; to identify risk and protective factors for the onset and persistence of these disorders; to describe patterns and correlates of service use for these disorders; and to lay the groundwork for subsequent follow-up studies that can be used to identify early expressions of adult mental disorders.

In addition to interviewing adolescents, information was collected from a parent or a parent surrogate to obtain an additional perspective on the adolescent's mental health and its correlates. Information from parents focused on the five adolescent disorders for which previous methodological research has most consistently shown that parental reports are important for making diagnoses: attention-deficit/hyperactivity disorder, conduct disorder, oppositional defiant disorder, major depressive episode, and dysthymic disorder.

The study contains four data files: (1) data for the adolescent household and school respondents; (2) data for the parents who responded to the long self-administered questionnaire; (3) data for the parents who responded to both the long self-administered questionnaire and the short telephone interview; and (4) diagnostic variables based on information collected from both adolescents and parents.

Demographic information includes age, citizenship status, country of birth, criminal history, ethnicity, grandparents' country of birth, language(s) spoken in the home, parents' country of birth, race, religion, and sex.