This presentation reviews environmental and genetic factors that relate to high density lipoprotein cholesterol, the most potent independent lipoprotein risk factor for coronary heart disease. Although at least three decades of work have focused upon the primary atherogenic lipoprotein, low density lipoprotein cholesterol (C-LDL), which has a strong positive association with coronary heart disease (CHD), it has only been in the past decade that detailed epidemiologic and biochemical studies have revealed that high density lipoprotein cholesterol (C-HDL) is the most potent lipoprotein cholesterol related to coronary heart disease; this relationship is, however, inverse.