In 1987, DeSoto appeared in the biographic film La Bamba. In that film, she portrayed Connie Valenzuela, the mother of Ritchie Valens, played by Lou Diamond Phillips. The next year, DeSoto collaborated with Phillips again in the 1988 biopic Stand and Deliver, where she portrayed Fabiola Escalante, the wife of Jaime Escalante (Edward James Olmos). Her performance garnered her an Independent Spirit Award for Best Supporting Female.