Mark McClellan served as administrator of the Centers for Medicare & Medicaid Services, and prior to that, as commissioner of the Food and Drug Administration beginning in November 2002. During 2001 and 2002, McClellan served in the White House as a member of the President's Council of Economic Advisers and was a senior policy director for health care and related economic issues. From 1998-99, he was deputy assistant secretary of the Treasury for economic policy, where he supervised economic analysis and policy development on a wide range of domestic policy issues.

McClellan also held a position as associate professor of economics at Stanford University. He was also a research associate of the National Bureau of Economic Research and a visiting scholar at the American Enterprise Institute. Additionally, he was a member of the National Cancer Policy Board of the National Academy of Sciences, associate editor of the Journal of Health Economics, and co-principal investigator of the Health and Retirement Study (HRS), a longitudinal study of the health and economic well-being of older Americans.

McClellan is a Member of the Institute of Medicine . He earned his M.D. from the Harvard-MIT Division of Health Sciences and Technology and his Ph.D. in Economics from MIT.