Allee Willis, one of the music industry’s most colorful figures, whose eclectic credits as a writer and co-writer included Earth, Wind & Fire’s “September” and the “Friends” theme song, died on Tuesday at a hospital in Los Angeles. She was 72.

The cause was cardiac arrest, her publicist, Ellyn Solis, said.

The animator and producer Prudence Fenton, Ms. Willis’s partner of 27 years, posted a photo on Instagram with the caption: “Rest in Boogie Wonderland,” referring to the Earth, Wind & Fire disco hit that Ms. Willis wrote with Jon Lind.

Ms. Willis, who grew up in Detroit, never learned to play music. But she was drawn to Motown as a child, and said she learned how to become a songwriter by sitting on the lawn outside the record company’s studios and listening to the rhythms seeping through the building’s walls.

“A lot of times I would learn a bass line and then I’d hear the records and I’d go, Oh, that was ‘I Heard It Through the Grapevine,’” she told The New York Times last year.