While the onset of symptomatic cardiovascular disease (CVD) typically occurs in middle age or later, the development of the underlying pathology is clearly a long-term process, and early-state lesions having been identified at autopsy even in children. Understanding the course of CVD risk development from childhood into middle age will clearly be valuable both in understanding the pathology of CVD and in targeting preventive measures most effectively. Furthermore, while genetic factors are agreed to play a significant role in the development of CVD, most genes contributing to interindividual variation in CVD risk will have relatively small effects on risk for any given individual, even though their aggregate effects contribute significantly to CVD risk in the overall population. Relatively little is known about the effects of genetic variants on the course of CVD risk factor development in individuals over time. The Bogalusa Heart Study (BHS), which began in 1973 as a study of CVD risk factors in children but evolved to cover the development of CVD risk factors from childhood into early middle age, offers an unparalleled resource for investigating the genetic factors influencing within-individual changes over time in quantitative factors, such as serum lipids and blood pressure, related to CVD risk.