It grew out of the reform activity during the 1960s on Capitol Hill, when new Members of Congress were elected. The PAC provided those members with ideas and votes to pass their preferred legislation.
After the 1972 election, the PAC membership included 20 of the first 25 newly elected freshman Democrats who supported Shirley Chisholm for President of the United States that year.
In the mid-1970s, the PAC began to move in a left-wing direction led by its new chair George Miller. Miller introduced resolutions criticizing U.S. policy in Angola and calling for the recognition of the People's Republic of China and a halt to the B-1 Bomber, which passed with solid Democratic support.
The PAC is one of the most prominent liberal caucuses in the House, and it is affiliated with the Democratic Party. The PAC has been an important force in pushing for progressive legislation, including civil rights, environmental protection, and labor rights.
The PAC has also played a significant role in electing progressive candidates to the House of Representatives. In the 2006 midterm elections, for example, the PAC spent over $100 million to help elect progressive Democrats to the House.