Preschool is an important developmental context for children of immigrants that can help them succeed in later life. In this study, we examine the association between preschool and academic school readiness among young children of Asian or Hispanic immigrant mothers. A secondary data analysis was conducted using data (n [is approximately] 1,550) collected in the Early Childhood Longitudinal Study-Birth Cohort. Results show that attending preschool (mostly prekindergarten or other center-based care) was associated with better academic school readiness at the year of participation among children of both Asian and Hispanic immigrant mothers; such beneficial associations were found at kindergarten entry among Asian children, but not Hispanic children. Furthermore, more-pronounced beneficial influences of preschool on academic school readiness were found at the year of participation among children of home language mothers in both groups, but such more-pronounced benefits were gone at kindergarten entry in both groups. These findings suggest that the differences between the two groups in maintaining the benefits from preschool may be associated with different home environments. Future research is needed to look specifically at the mechanisms of how attending preschool is related to academic school readiness among children of immigrants. (author abstract)