The Georgia Cardiovascular Twin Study is a longitudinal study of biobehavioral antecedents of cardiovascular disease in youth and young adults, including around 500 twin pairs with roughly equal numbers of African Americans and European Americans. Focus of study includes the longitudinal change in relative influence of genetic and environmental factors (especially chronic stress) on development of risk factors for cardiovascular disease. Approaches include quantitative genetic modeling of phenotypic twin data as well as the examination of the influence of polymorphic variation in candidate genes and their potential interaction with environmental factors on these risk factors. Future work will expand the scope of the study to investigating the impact of chronic stress as measured by indices of the hypothalamus-pituitary-adrenal axis and the sympathetic nervous system on preclinical markers of cardiovascular disease, essential hypertension and type 2 diabetes.