Yellen was sworn in at a private ceremony Monday morning with her husband by her side. The 67-year-old took the top spot last week, so Monday's event was purely ceremonial.
Yellen is a former UC Berkeley economist and former president of the San Francisco Federal Reserve Bank. She succeeds Ben Bernanke and is the first woman ever to lead the Federal Reserve.
Yellen is expected to continue the fed's policy of maintaining low interest rates while scaling back stimulus programs.