Low levels of high density lipoprotein (HDL) cholesterol have been associated with an increased risk of coronary heart disease. In the previous chapter, we have described the presence of distinct apolipoprotein A-I containing HDL particles beginning with small discoidal precursor HDL particles known as preβ-1 HDL and ending with large mature spherical HDL known as alpha 1 HDL. In this chapter, we review our own concepts of the metabolism and remodeling of these HDL particles with emphasis on what we have learned from observations in various inherited disorders of lipoprotein metabolism. The roles of apolipoprotein A-I production, secretion, combination with phospholipids, cellular cholesterol and phospholipid efflux transporters, and cholesterol esterification will be reviewed. In addition, the roles of lipoprotein lipase, hepatic lipase, endothelial lipase, and cholesteryl ester transfer protein on HDL particle metabolism will be discussed as will those of scavenger receptor B1, apolipoprotein recycling, and renal clearance of apolipoprotein A-I. In addition, we will relate our finding to coronary heart disease risk.