The purpose of this longitudinal study was to examine the expressive language of low-income Latino children and the factors that may influence their language development. More specifically, this study was designed to determine the effect of acculturation, caregiver-child interaction, developmental status, language dominance, language exposure, and sociodemographic risk on children's expressive language. The following analytical procedures were used to carry out the study: (1) Hierarchical Linear Modeling analyses were conducted to examine the effects of dominance language, sociodemographic risk, acculturation, and developmental status on vocabulary growth in children's dominant language. (2) Pearson correlations and descriptive analyses were conducted to examine the effects of these same five factors on children's language in English and Spanish at particular measurement points. The data obtained from these analyses support the hypothesis that caregiver-child interaction are affected by distal factors such as acculturation and sociodemographic risk and consequently children's expressive language outcomes. The results also showed significant results in the rate of vocabulary growth of children in their dominant language and that there were significant correlations between vocabulary and relative amount of language exposure in English and Spanish. The descriptive analyses suggest that distal as well as proximal factors such as caregiver-child interaction influence language growth and outcomes in English and Spanish. (author abstract)