Yellen sworn in as US Fed chair
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.