In 2012, Berenson completed a three-year term on the Medicare Payment Advisory Commission, the last two years as vice chair. From 1998 to 2000, he was in charge of Medicare payment policy and private health plan contracting in the Centers for Medicare and Medicaid Services. Previously, he served as an assistant director of the White House Domestic Policy Staff under President Carter.

Berenson is a board-certified internist who practiced for 20 years, the last 12 years in a Washington, DC, group practice. While practicing he helped organize and manage a successful preferred provider organization serving the Washington, DC, metropolitan area. He is coauthor of The Managed Care Blues & How to Cure Them with Walter Zelman, and Medicare Payment Policy and the Shaping of U.S. Health Care, with Rick Mayes. He publishes frequently in numerous publications, including the New England Journal of Medicine, Health Affairs, New York Times, and New Republic.

Berenson is a graduate of the Mount Sinai School of Medicine, a fellow of the American College of Physicians, and on the faculty at the George Washington University School of Public Health.