Research Findings: Home literacy involvement (e.g., shared book reading) has been linked to enhanced cognitive development and school readiness during early childhood. Furthermore, precursory reading and math skills are key predictors of high school achievement. This study examined prospective relations between Mexican mothers' English proficiency, their home literacy involvement, and their children's school readiness (i.e., preschool reading and math scores). A large, nationally representative sample of preschool-age Mexican American children (N = 826) was used to test a theoretically derived path analysis that demonstrated that mother-reported home literacy involvement mediated the relation between mother-reported English proficiency and children's reading achievement, but not math. Results were evident even after key family and child characteristics were controlled. Practice or Policy: Findings suggest that Mexican American children's early education and development may be enriched by family literacy programs that enhance their mothers' English proficiency and increase the frequency of home literacy activities.