"My colleagues and I are acutely aware of how much workers have lost in the past five years," Yellen said in a speech prepared for an AFL-CIO conference Monday.
"With employment so far from its maximum level and with inflation currently running, and expected to continue to run, at or below the [central bank's] 2 percent longer-term objective, it is entirely appropriate for progress in attaining maximum employment to take center stage in determining the [monetary] policy stance," she said.
The Wall Street Journal reported Monday Yellen pointed to exogenous headwinds that are slowing the U.S. economy, including the sovereign debt crisis and economic slowdown in Europe.
She also said the 6.5 percent threshold the Fed recently said was a target unemployment rate that would signal time for a monetary policy change was a guideline, not a set trigger for change.
If the unemployment rate falls below 6.5 percent, "action is possible but not assured," MarketWatch reported she said.