Early oral language development lays an essential foundation for academic and socioemotional competencies but is vulnerable to the impact of family stress. Despite robust evidence that family stress affects early oral language development in monolingual samples, little is known about whether the family stress processes affecting language acquisition are similar among dual language learners. Furthermore, although Mexican American families often face stressors related to their ethnic minority and immigrant status, no studies to date have tested whether exposure to sociocultural stressors may likewise have negative consequences for early language acquisition. The present study examined whether financial and sociocultural stressors were associated with maternal stress perception, parenting sensitivity, and child Spanish and English receptive vocabulary at child age 3 and 4.5 years. Participants included 322 low-income Mexican American mothers and their children followed from pregnancy through 4.5 years postnatal; most mothers preferred to speak Spanish (82%). Results of a path model indicated that links between family stress and child receptive vocabulary varied by language (Spanish or English) and stress type (financial or cultural). Specifically, Spanish acquisition was more closely related to the quality of mother-child interactions, whereas English acquisition was more susceptible to the direct impact of family stress. The consequences of family stress on children's vocabulary acquisition were evident earlier in development for Spanish than English, and appeared more pronounced for financial versus sociocultural stressors. Findings underscore a need to attend to the impact of poverty on children's Spanish and English language development in low-income, Mexican American children.