The Cardiovascular Health Study (CHS) is a population-based longitudinal study of coronary heart disease and stroke in adults aged 65 years and older. Just over 5200 men and women (5201) were recruited from four communities: Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Pittsburgh, Pennsylvania. An additional 687 African Americans were recruited after the initial baseline survey. The population from the Pittsburgh Field Center was entirely urban; and the other three Field Centers recruited a mixture of urban and rural populations.