Subjects completed three laboratory stressors: a video game task, a structured social interview, and the cold pressor. Stress responsivity was assessed, with particular interest being paid to systemic vascular resistance (SVR). Left ventricular mass (LVM) was also assessed. Sophisticated environmentally and genetically informative analyses permitted quantification of environmental impact upon systemic vascular resistance responsivity and left ventricular mass. It was hypothesized that environmental influences (SES) accounted for a greater proportion of the variance in systemic vascular resistance responsivity and left ventricular mass in African Americans than Caucasian Americans. The hypothesis that systemic vascular resistance responsivity was a pathway through which SES exerted its influence on left ventricular mass was also tested.