In 1973 standardized blood pressure, height, and weight were measured in all 14-19 year old students of Bourbon County High School in Kentucky. Additional information collected included age, date of birth, sex, and race. In 1978 a five year follow-up study was undertaken of all adolescents 14-15 years old at the time of the initial survey and of selected 16-19 year olds who were in the high, intermediate, and low ranges of the blood pressure distributions. Follow-up measurements included weight, height, and blood pressure in all subjects, and sodium excretion, serum cholesterol, glucose, triglycerides, exercise, and uric acid concentrations, electrocardiograms, and echocardiograms in the older group. In 1984 the follow-up also included information on socioeconomic variables, medical and family histories, smoking, exercise, life events, coronary-prone behavior, and anxiety. Plasma renin activity and plasma aldosterone were measured before and after treadmill exercise in those young adults with relatively high and relatively low blood pressures to determine if the renin-aldosterone axis is suppressed before the appearance of hypertension. Studies were continued on physiologic, psychosocial, and behavioral risk factors for hypertension, age-related trends in cardiovascular risk factors over time, correlates of elevated blood pressure, and the early cardiac consequences of high blood pressure.