The purpose of this study was to examine adrenocortical activity (basal, diurnal variation, andresponses to social stressors) in adolescents at risk for psychopathology. Salivary cortisol levelswere examined in normally developing and at-risk youth with internalizing and externalizingsymptoms ranging from subclinical to clinical levels. Adolescents showed expected patterns ofdiurnal variation, with high early morning cortisol levels and a pattern of decline throughout theday. Females showed higher midday and late afternoon levels than males, and these patternsinteracted with risk status. Internalizing problems sometimes were associated with gradual ratherthan steep declines in basal cortisol production. Both immediate and delayed cortisol reactivity toa social performance stressor were associated with internalizing symptoms. There was noevidence of relations between externalizing problems and underarousal of thehypothalamic–pituitary–adrenal (HPA) system. These and other results suggest thatgender is an important moderating factor linking psychopathology, development, and context withHPA axis functioning in adolescence.