For Dr. David E. Hayes-Bautista, one baby’s story says it all. Selene Segura Rios, a flu-stricken 18-month-old whose working parents couldn’t afford the ER and who lived far from the nearest doctor, died of dehydration under the inadequate care of an unlicensed healer—not in a Third World country but in the United States. Selene, like many Latinos, lacked access to proper health care, a problem Hayes-Bautista has been fighting his whole career. As a grad student in the 1970s, Hayes-Bautista brought needed care to desperate Californians as a founding director of La Clinica de la Raza, a chain of low-cost medical centers that treats more than 100,000 patients a year. An engineer by training, whose compassion and love of hard data led him into the field of medical sociology, Hayes-Bautista, 63, is now director of the Center for the Study of Latino Health and Culture at UCLA, and his influence is felt nationwide. His research helps policymakers get to the heart of medical problems bedeviling the Latino community—so that babies like Selene become an anomaly and not just one more statistic.