The "Latino Health Paradox" denotes a well-established trend wherein foreign-born Latino immigrants arrive with protective health benefits which dissipate and sometimes reverse into health disparities in the second and subsequent generations. The origins and mechanism behind this paradox remain poorly understood. This study investigates whether physiological stress profiles in children of Latina immigrants (CoLIs) as compared with the children of Latina Americans (CoLAs) and of non-Latina Americans (ConLAs) might help explain how health advantages can be lost during acculturation to even result in health disparities. Because studies of ethnicity/nativity often confound poverty and ethnicity/nativity groups, we also examine differences in physiologic stress profiles by income. We focus on physiologic profile differences between ethnicity/nativity groups and by poverty category at home and in Early Childhood Education (ECE) environments. Using multi-level modeling, we compare morning and afternoon salivary cortisol levels between ECE and home environments in 256 children (32% CoLIs), while controlling for child, child care, and teacher characteristics. Results demonstrated that overall, cortisol on child care mornings was lower than on home mornings, and that among children living in poverty home and childcare morning cortisol differed less than for children not living in poverty. We find that CoLIs exhibit a flatter slope on child care days than do ConLAs. We also find that among children in classrooms with lower average poverty exposure, cortisol decline across the day is steeper on child care days. Importantly, teacher language may act as a buffer to CoLIs on child care days, resulting in a steeper decline at childcare. Implications for policy and practice, including supporting the availability of bilingual teachers are discussed. (author abstract)