"Education levels have historically lagged in low- and moderate-income communities, particularly communities of color," Yellen said in prepared remarks on workforce development to a conference in Washington.

The Fed chief did not mention monetary policy or the economic outlook in her speech. The central bank has repeatedly said that one of the barriers to both employment and growth is a lack of appropriate education and skills training.

The unemployment rate currently stands at 4.7 percent for the nation as a whole, which is near what many Fed officials consider full employment. However, that masks pockets of higher unemployment.

Unemployment rates averaged 13 percent in low- and moderate-income communities between 2011 and 2015, Yellen noted, compared to 7.3 percent in higher-income communities. Where minorities made up a majority of the population, that percentage rose to 14.3 percent over the same period.

Given higher education levels lead to higher-paying jobs, she said it was vital to invest in education. But it was also important to provide opportunities for those who do not have advanced degrees.

"Educational programs and training that lead to better paying and more steady work are crucial for people without college degrees, particularly lower-income workers," Yellen said.