In 2002, Gradison was appointed by the Securities and Exchange Commission as a founding Member of the Public Company Accounting Oversight Board (PCAOB); this Board was created by the Sarbanes-Oxley Act of 2002. Gradison was unanimously reappointed to a full five-year term in August 2004, and served as Acting Chairman from December 2005 to July 2006. He remained a PCAOB Board member until February 2011. He was named commissioner of the Medicare Payment Advisory Commission (MedPAC), which is an independent Congressional agency established by the Balanced Budget Act of 1997 (P.L. 105-33) to advise the U.S. Congress on issues affecting the Medicare program. He served as a MedPAC commissioner for six years. MedPAC's biography of Gradison cites his previous experience as a member of the Health Subcommittee of the Committee on Ways and Means; his Vice Chairmanship of the U.S. Bipartisan Commission on Comprehensive Health Care (“Pepper Commission”); his service as Assistant to the Secretary of Health, Education, and Welfare; and his Vice Chairmanship of the Commonwealth Fund Task Force on Academic Health Centers.