The hypothalamic-pituitary-adrenal axis is thought to play a role in the pathogenesis of depression. In the study reported here, we tested the hypothesis that parenting behavior moderates the relation between parents' lifetime history of depression and their offspring's cortisol reactivity to a psychosocial stressor. We exposed 160 preschool-age children to stress-inducing laboratory tasks, during which we obtained four salivary cortisol samples. Parents completed clinical interviews and an observational parent-child interaction task. The results confirmed our hypothesis: The offspring who evidenced high and increasing cortisol levels were those whose parents had a history of depression and demonstrated hostility toward their child. This moderating effect was specific to offspring who were exposed to maternal depression during the first few years of life. As do findings in animals, results of this study underscore the importance of the early rearing environment in the intergenerational transmission of stress sensitivity.