Dysregulated emotions are central features of psychiatric disorders associated with both externalizing problems (aggressive, antisocial behaviors) and internalizing problems (anxiety, depression). Adolescence is a critical juncture in the development of these disorders because of the increased incidence and differentiation of clinical problems particularly along gender-based lines. This is a biobehavioral, longitudinal investigation of the role of emotion in the development of psychopathology in adolescence. The focus is on socialization experiences and biological processes that contribute to emotion dysregulation and disorder. Younger (11-13) years) and older (14-16 years) male and female adolescents are followed over time to assess outcomes (psychiatric and psychological problems; adaptive functioning). Groups studied include (1) comorbid externalizers and internalizers, (2) externalizers, (3) internalizers, and (4) asymptomatic youth. Longitudinal analyses will examine factors that contribute to continuation, exacerbation, shifts, or improvement in symptoms over time. Time 1 data collection is complete and 30% of Time 2 cases have been seen. The current anticipated number of patient days per year is 150 for adolescents and mothers. Data collection will be completed by January, 2003.