Given the increase of Spanish- and English-speaking bilingual students in US schools, identifying the predictors of reading in this group of students is of significant importance to developing appropriate screening measures and intervention strategies. Thus, the current study evaluated the pattern of language preference in an elementary school bilingual (Spanish-English) population and its relationship with expressive and receptive vocabulary, and broad reading ability in English and Spanish. Participants were 58 Latino students ranging in age from 7 years, 5 months to 11 years, 1 month (M = 8.98, SD = .98) with 48% born in the United States. Results indicated that English expressive vocabulary partially mediated the relationship between outside language preference and English broad reading ability. In contrast, neither Spanish expressive nor receptive vocabulary mediated the relationship between outside language preference and Spanish broad reading ability.