This paper describes the implementation of the National Institute of Mental Health Methods for the Epidemiology of Child and Adolescent Mental Disorders (MECA) study's goals of measuring risk factors and competence. The emphasis is on the development and testing of the measures. Relevant constructs for measurement of risk and competence in relation to psychopathology were selected and pilot tested prior to the field trials. A structured interview was developed and field tested using lay interviewers. Using the full sample from the field trials (n = 1285 caretaker-youth pairs), sample means, standard deviations, internal consistencies, parent-youth agreement, and associations with childhood disorder were computed. Descriptive statistics reveal a range of scores and means consistent with norming samples, when available, Internal consistencies were moderate to high. Parent-youth agreement on factual items was excellent and on scales was consistent with the literature. Several strong associations were found between risk factors and disorder, although most were related to disorder in general and not specific to a diagnostic category. This instrument provides a means of obtaining data that will be useful to researchers conducting epidemiologic and clinical studies designed to contribute to the understanding of mental disorders in children and adolescents, including nosology, risk factors, context, adaptive functioning, and treatment.