Ronnie Gilbert, the female voice in the influential 1950s folk quartet the Weavers, which also included Pete Seeger, Lee Hays and Fred Hellerman, has died at age 88. Gilbert died of natural causes on Saturday, at a retirement home in the San Francisco Bay Area suburb of Mill Valley.

The four, with Gilbert singing contralto, came together in 1948 and are credited with a folk revival that helped spawn such performers as Bob Dylan, the Kingston Trio and Peter, Paul and Mary. But the group’s leftist political views put them on the radar of the McCarthy-era anti-communist movement and the group lost their recording contract in 1951.

“We sang songs of hope in that strange time after World War II, when already the world was preparing for Cold War,” Gilbert said in an interview in 1982 for the documentary The Weavers: Wasn’t That a Time. “We still had the feeling that if we could sing loud enough and strong enough and hopefully enough, it would make a difference.”

Read More: Ronnie Gilbert, Clarion Voice Of Folk Band The Weavers, Dies At 88 : The Two-Way : NPR