The authors examined the relevance of communalism, operationalized as a cultural orientation emphasizing interdependence, to maternal prenatal emotional health and physiology and distinguished its effects from those of ethnicity and childhood and adult socioeconomic status (SES). African American and European American women (N = 297) were recruited early in pregnancy and followed through 32 weeks gestation using interviews and medical chart review. Overall, African American women and women of lower socioeconomic backgrounds had higher levels of negative affect, stress, and blood pressure, but these ethnic and socioeconomic disparities were not observed among women higher in communalism. Hierarchical multivariate regression analyses showed that communalism was a more robust predictor of prenatal emotional health than ethnicity, childhood SES, and adult SES. Communalism also interacted with ethnicity and SES, resulting in lower blood pressure during pregnancy for African American women and women who experienced socioeconomic disadvantage over the life course. The effects of communalism on prenatal affect, stress, and physiology were not explained by depressive symptoms at study entry, perceived availability of social support, self-esteem, optimism, mastery, nor pregnancy-specific factors, including whether the pregnancy was planned, whether the pregnancy was desired after conception, or how frequently the woman felt happy to be pregnant. This suggests that a communal cultural orientation benefits maternal prenatal emotional health and physiology over and above its links to better understood personal and social resources in addition to economic resources. Implications of culture as a determinant of maternal prenatal health and well-being and an important lens for examining ethnic and socioeconomic inequalities in health are discussed.