The Georgia Cardiovascular Twin Study is a longitudinal study of biobehavioral antecedents of cardiovascular disease in youth. It includes roughly equal numbers of African Americans and European Americans, with a total of > 500 twin pairs. Focus of the study is the change in relative influence of genetic and environmental factors on development of risk factors for cardiovascular disease. Future work will explore the influence of polymorphic variation in candidate genes and their potential interaction with the environment on these risk factors.