In order to determine the biochemical mechanisms responsible for the dietary fat-mediated change in plasma lipoprotein cholesterol level and the risk of developing coronary heart disease (CAD), this study will determine the acute and chronic effet of dietary fat composition on a) the level, composition, and density spectrum of lipoprotein cholesterol and triglycerides in fasting and postprandial plasma, b) the postprandial lipemia-induced transfer of cholesterol mass from endogenous lipoproteins into postprandial chylomicrons in vivo and in vitro, and c) the in vitro, intraplasmic metabolic activities that promote reverse cholesterol transport in vivo.