Yellen sworn in at Federal Reserve

Janet Yellen officially became the first female head of the Federal Reserve on Monday, becoming one of the world's most powerful economic figures.

Yellen was sworn in to lead the central bank following the exit of Ben Bernanke, whose term expired at the end of January after eight years of leading the institution. She was sworn in by Daniel Tarullo, a Fed governor.

Yellen is set to lead the institution until 2018, and takes it over at a critical juncture. The Fed is currently trying to unwind its extreme economic accommodating, shrinking the size of its monthly bond purchases as the economy continues to improve.

One of Yellen's biggest jobs will be navigating that exit in a way that does not upend the recovery, while at the same time dealing with a Congress that has grown increasingly skeptical of the Fed's methods, particularly among Republicans.

Yellen was nominated by President Obama in October, and confirmed by the Senate in January.