Julie, the runaway daughter of a San Francisco prostitute mother, had been arrested in LA for vagrancy.
Julie, Pete and Linc were asked to form a "youth squad" and blend in with the counterculture to fight crime. "The Mod Squad" became the first cop show to attract a young audience. The show raised awareness of the issues of the day, like reace, drugs, and the Vietnam War.
Peggy was the last of 17 actresses to audition for the part. "The Mod Squad" producers had practically decided on another actress and only auditioned Peggy as a courtesy. But when producer Aaron Spelling saw her he exclaimed, "Is that a face? Is that a face!" He later said, "One look, even before we saw her on screen and I knew we had our girl." Spelling's partner, Danny Thomas, said, "She had a kind of mystery that got to me."
Peggy brought a laid-back attitude to playing Julie. She told Life magazine in 1971, "I'm in a very, very safe position... I don't take chances. I have my look down. Kind of moping around with my long straight hair and just holding my eyes big.
"I've gotten away with it, and it's fantastic."