The Rancho Bernardo Study (RBS) was founded by Elizabeth Barrett-Connor, MD, in 1972 as a population-based heart disease risk factor screening survey of all residents of the community of Rancho Bernardo, California at that time. This study was part of the nation-wide Lipid Research Clinic (LRC) Prevalence program, a multi-centered collaborative study funded by the National Heart, Lung and Blood Institute. All Rancho Bernardo residents were invited to participate in the free examinations that were conducted in a trailer in a supermarket parking lot. Data collected from participants at this visit (Visit 1 of the RBS) included their name, address, phone number, date of birth; demographic variables such as sex, marital status, occupation of head of household, education and race; physical characteristics such as weight, height, blood pressure; personal and family history of diseases such as heart disease, diabetes, stroke, and personal use of medications for various illnesses; laboratory determination of fasting total cholesterol, triglycerides, and glucose; and finally, questions about a few health habits such as cigarette smoking, and egg and milk consumption were asked. Visit 1 was completed in 1974. There were 6,339 participants in Visit 1; most continued to participate via additional research visits and annual mailers over the following 47 years.