The present investigation examines mediated pathways from pubertal development to changes in depressive affect and aggression. Participants were 100 white girls who were between the ages of 10 and 14 (M=12.13, SD=0.80); girls were from well-educated, middle-to upper-middle class families, and attended private schools in a major northeastern urban area. Three aspects of pubertal development were examined: (a) estradiol categories tapping gonadal maturation; (b) dehydroepiandrosterone sulfate (DHEAS) levels indicating adrenal maturation; and (c) pubertal timing (early vs. other). Three potential mediators were also examined: emotional arousal, attention difficulties, and negative life events. Tests of mediated models indicated that early pubertal timing predicted higher emotional arousal which subsequently predicted increased depressive affect. Negative life events, and possibly attention difficulties, mediated the associations of both estradiol category and DHEAS with aggression. These findings highlight the potential for more intensive investigation of gonadal and adrenal processes in explaining affective changes at puberty.