All ninth-graders entering two large Baltimore high schools in year 1 and year 2 of the study were screened to yield the 240 subjects in the cohort. Initial screening included data on blood pressure, height, weight, health habits, personality, medical history, and health care utilization. Baseline exam included data on basal blood pressure, aerobic exercise stress, cognitive stress, interpersonal stress, ambulatory blood pressure, echocardiogram, physical activity, and Type A personality. The parents were also interviewed to assess family blood pressure status, health history, health care utilization and dietary habits including sodium intake. Students were re-examined at twelve and 24 months.