Epidemiologists have shown how birth outcomes are generally robust for immigrant Latina mothers, despite often situated in poor households, advanced by their strong prenatal and nutritional practices. But little is known about (1) how these protective factors may differ among Latino subgroups, (2) the extent to which birth outcomes, ongoing maternal practices, and family supports advance Latino toddlers' health and physical growth, and (3) whether the same processes advance toddlers' early cognitive growth. We drew on a national probability sample of 8,114 infants born in 2001, including 1,450 of diverse Latino origins. Data come from birth records, maternal interviews when the child was 9 and 24 months of age, and direct assessments of health status, physical growth, and cognitive proficiencies. Descriptive analyses compared Mexican-heritage and other Latino mothers and toddlers relative to middle-class whites. Multivariate regression techniques identified predictors of child health, weight, and BMI, as well as cognitive proficiencies at 24 months. Infants of Mexican-heritage or less acculturated Latina mothers displayed robust birth outcomes, compared with other ethnic groups. The low incidence of premature births and low birthweight among these mothers continued to advance their cognitive growth through 24 months of age. Yet Latino children overall displayed smaller gains in cognitive proficiencies between 9 and 24 months, compared with middle-class populations, attributable to Latinas' lower levels of maternal education, weaker preliteracy practices, and a higher ratio of children per resident adult. Health practitioners should recognize that many Latina mothers display healthy prenatal practices and give birth to robust infants. But these early protective factors do not necessarily advance early cognitive growth. Screening practices, early interventions, and federal policy should become more sensitive to these countervailing dynamics