This study addressed the question of what effect bilingual preschool education has on the Spanish and English language development of Spanish speaking children. This question was addressed by measuring the language proficiency of children enrolled in a bilingual preschool program and children who stay at home during the day. Three dimensions of language proficiency were examined: language reception, production, and verbal complexity. Using a repeated measures design, it was found that children enrolled in preschool gained proficiency in English at a faster rate while maintaining a similar level of Spanish proficiency as those children who stay at home during the day. Results of this study are discussed in terms of current issues in the early childhood education of non-English-speaking children.