Janet Yellen has been sworn in to succeed Ben Bernanke, becoming the first woman to lead the US Federal Reserve in its 100-year history.
Yellen, who was confirmed by the US Senate last month, was sworn in by Fed Governor Daniel Tarullo, the senior member of the Fed's seven-member board.
She took the oath in a brief ceremony in front of a fireplace in the Fed's board room. Her husband, Nobel-winning economist George Akerloff, was present as were other board members and staff.
The 67-year-old made no remarks at her swearing in but did smile to acknowledge the applause of the assembled group.
Nominated by President Barack Obama on October 9, her four-year term as chairman will end on February 3, 2018.