The dysregulated experience and expression of emotion is implicated in psychiatric disorders associated both with 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 during this time period. 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 in male and female youths between 11 and 16 years of age. Groups studied include (1) comorbid externalizers and internalizers, (2) externalizers only, (3) internalizers only, and (4) asymptomatic youth. The adolescents are assessed again two years later, with instruments and paradigms similar to those used at Time 1. One theme pertains to the integration and disconnection of emotions across systems (e.g., physiological and self-report of experience), and how different patterns of emotion relate to psychopathology. A second theme pertains to development changes in how disorders are manifested (e.g., increased differentiation along gender specific pathways). The anticipated number of patient days per year is 240 for adolescents and mothers, and 120 days for fathers.