For a sample of low-income, Spanish-speaking Mexican-American families (n = 72), we investigated associations between family involvement in school-based activities and children's literacy in their preferred language (English or Spanish) during early elementary school. We gave special attention to the potential moderating role of teacher fluency in Spanish. Between kindergarten and third grade, family involvement in school-based activities increased for children who displayed early literacy problems. The rate of increase was greater for children who consistently had bilingual teachers than for children who did not. In turn, increased family involvement predicted better literacy skills at third grade, particularly for children who struggled early. We discuss these results in light of recent recommendations to increase the number of elementary school teachers who are fluent in Spanish and English. (Contains 4 figures and 4 tables.)