The frequently observed link between maternal depressive symptoms and heightened maternal reporting of adolescent externalizing behavior was examined from an integrative, systems perspective using a community sample of 180 adolescents, their mothers, fathers, and close peers, assessed twice over a three-year period. Consistent with this perspective, the maternal depression-adolescent externalizing link was found to reflect not simply maternal reporting biases, but heightened maternal sensitivity to independently observable teen misbehavior as well as long-term, predictive links between maternal symptoms and teen behavior. Maternal depressive symptoms predicted relative increases over time in teen externalizing behavior. Child effects were also found, however, in which teen externalizing behavior predicted future relative increases in maternal depressive symptoms. Findings are interpreted as revealing a tightly-linked behavioral-affective system in families with mothers experiencing depressive symptoms and teens engaged in externalizing behavior, and further suggest that research on depressive symptoms in women with adolescent offspring should now consider offspring externalizing behaviors as a significant risk factor.