Greenspan, 78, took the oath of office Saturday at the Colorado home of former President Gerald Ford (search), the Federal Reserve said. Vice President Dick Cheney administered the oath to Greenspan in a private ceremony.
Witnesses included Betty Ford and Greenspan's wife, Andrea Mitchell, the Fed said in a statement Monday.
President Bush nominated Greenspan to a fifth term on May 18. He was confirmed by the Senate last week.
Greenspan was first nominated as Fed chairman in 1987 by President Ronald Reagan to succeed chairman Paul Volcker (search). Greenspan was renominated to the Fed post once by Bush's father and twice by President Clinton.
Greenspan has told friends that he intends to retire when his separate 14-year term as a Fed board members runs out Jan. 31, 2006.
Fed policy-makers meet next to discuss interest rate policy. Many economists widely expect the Fed to raise rates at the June 29-30 meeting for the first time in four years. The Fed's main lever to influence economic activity is now at a 46-year low of 1 percent.