The Government Accountability Office (GAO) is the non-partisan audit, evaluation, and investigative arm of Congress, and an agency in the Legislative Branch of the United States Government. The GAO was established by the Budget and Accounting Act, 1921 (Public Law 67-13, 42 Stat. 20-27, June 10, 1921). This Act required the head of GAO to investigate "all matters related to the receipt, disbursement, and use of public funds," and make reports to the President and Congress with "recommmendations looking to greater economy or efficiency in public expenditures" (Sec. 312(a), 42 Stat. 25-26). According to GAO's current mission statement, the agency exists to support the Congress in meeting its Constitutional responsibilities and to help improve the performance and ensure the accountability of the federal government for the American people.

The GAO is headed by the Comptroller General of the United States, a unique non-partisan position in the U.S. Government. The Comptroller General is appointed by the President, by and with the advice and consent of the Senate for a 15-year, non-renewable term. The President selects a nominee from a list of at least three individuals recommended by an 8 member commission of congressional leaders. The Comptroller General may not be removed by the President, but only by Congress through impeachment or joint resolution for specific reasons. Since 1921, there have been only 7 Comptrollers General, and no formal attempt has ever been made to remove a Comptroller General. The long tenure of the Comptroller General and the manner of appointment and removal gives GAO a continuity of leadership and independence that is rare within government.

The position is currently filled by David M. Walker, a former Arthur Andersen partner and a Labor Department official in the Administrations of Presidents Ronald Reagan and George Bush. The seventh Comptroller General of the United States, Mr. Walker was appointed by President Clinton, and began serving his 15-year term in 1998.