Trends in blood pressure, serum lipids, and cigarette smoking were described in nationally representative samples of adolescents ages 12 to 17 and in young adults ages 18 to 24 using data from surveys conducted from 1960 to 1984 by the National Center for Health Statistics (NCHS). Trends in blood pressure, serum lipids, cigarette smoking, and obesity were described in nationally representative samples of older adults ages 35 to 75 using NCHS survey data. The national surveys used included National Health Examination Surveys (NHES-I and III), the National Health and Nutrition Examination Surveys (NHANES I and II) and Hispanic NHANES. The secular trends in these risk factors were contrasted by subgroupings of age, race, sex, family income, and education. The correlates of these risk factors were determined and secular changes over time were identified and quantified. Risk factor values and their correlates in the national population sample were contrasted with the three Hispanic populations surveyed in the Hispanic Health and Nutrition Examination Survey (HHANES). Statistical methodologies were refined including statistical software for the analysis of complete sample survey data, model fitting strategies to characterize the secular trends across four national surveys, and guidelines for the choice of analytical strategies.