Objective: Race/ethnicity and socioeconomic status are both associated with stress physiology as indexed by cortisol. The present study tested the extent to which racial/ethnic disparities in cortisol reactivity are explained by socioeconomic status. Method: The sample consisted of 296 racially and socioeconomically diverse children ages 8–11 (47% boys). Mothers reported on children’s stressors and socioeconomic status; salivary cortisol levels were assessed before and after the Trier Social Stress Test. Results: Results demonstrated that racial group differences in cortisol reactivity were partially accounted for by differences in socioeconomic status, but racial group differences in cortisol recovery were not. Conclusions: These findings suggest that cumulative effects of stress and disadvantage may result in differences in stress response physiology as early as middle childhood, and that race-specific mechanisms account for additional variance in cortisol reactivity and recovery.