Recent studies on differences in infant mortality and low birth weight (LBW) among non-Hispanic whites, African Americans, and Mexican Americans were reviewed. Despite similar socioeconomic profiles, infant mortality among Mexican Americans (8/1000 live births) is less than half that of African Americans (18/1000 live births). In fact, the rate for Mexican Americans is identical to that of non-Hispanic whites. The data for LBW follow a similar pattern. What accounts for this unexpectedly low frequency of poor birth outcomes among Mexican Americans, especially given their economic disadvantages, reduced access to prenatal care, and exposure to discrimination based on ethnicity? Does adherence to a traditional Mexican cultural orientation protect otherwise high-risk Mexican Americans from poor pregnancy outcomes, as has been suggested? What is the "protective" social and psychological content of a traditional Mexican cultural orientation? And what are the implications of this line of reasoning for understanding the excess risk for poor birth outcomes among African Americans? This article explores these and related questions and concludes that new conceptual models are needed to guide research in this area.