The study examined whether psychosocial intervention for children diagnosed with a disruptive behavior disorder (DBD; n = 84) changed concentrations of cortisol and testosterone across a 3-year follow-up when compared to a matched, nonclinical, healthy comparison (HC; n = 69) group. Boys and girls (6-11 years) with a DBD were randomly assigned to one of two arms of a multimethod intervention. Hierarchical linear modeling revealed that children undergoing psychosocial intervention for a DBD experienced a significant decline in diurnal cortisol change over time (p < .05) when compared to the HC condition. Boys with a DBD diagnosis had significantly lower mean cortisol concentrations prior to treatment (p < .05) and showed a significantly steeper increase in mean cortisol over time (p < .05) when compared to HC boys. Treatment effects for diurnal cortisol change were replicated in the boys-only analysis. No treatment effects were noted for testosterone in either analysis.