In the Spring of 1978 a total of 10,423 children, ages 6-8 were screened. A subsample was invited to join the study of blood pressure measurement. The sample was selected as follows: all children in the top five percent of the initial systolic blood pressure distribution; all children in the bottom five percent of the initial systolic blood pressure distribution; a random sample of one in two of the remaining Black children; a random sample of one in nine of the remaining white children; and all the remaining children of other races. Included were families of about 200 Native American children. Of 2,641 selected children, 878 refused leaving a sample of 1,753. Baseline data on age, race, sex, triceps skinfold thickness, dietary history, urinary sodium and potassium excretion, physiological measures, life event changes, medical history, demographic data and body size measurements of children and their parents were collected at the first home interview conducted between 1978 and 1979. The children were followed twice per year in 1978 to 1980 and 1982 to 1985 for blood pressure and body size. Annual measurements were made of blood pressure, height, weight, skinfold thickness, and body girths. Screenings continued through early 1991 when the cohort was 19-21 years of age.