The CAPA interview glossary that provides detailed operational definitions of symptoms and severity ratings is described, and psychometric data and further developments of the interview are presented. The assessment shows that across 5,962 parent-child interviews, the core sections of the CAPA (psychiatric symptoms, functional impairment, demographics, and family structure and functioning) took an average 59 minutes for children and 66 minutes for parents. Test-retest reliability for diagnoses ranged from k=0.55 for conduct disorder to k=1.0 for substance abuse/dependence. Validity as judged by 10 different criteria was good. Developments of the CAPA include a shorter "gateway" version that uses core symptoms as screen items; a Spanish version; and versions for twin studies, use with young adults, and preschool-age children. The authors conclude that there is a place in both research and clinical settings for a rigorously operationalized interview (such as the CAPA) that focuses on ensuring that respondents understand what is being asked and on clearly defining levels of symptom severity and functional impairment. 2 tables, 4 figures, and 33 references