Research Findings: Using nationally representative data from the Early Childhood Longitudinal Study-Kindergarten cohort, this study investigates whether socioeconomic status (SES) moderates the association between center-based early childhood education (ECE) and English proficiency at kindergarten entry for 1st- and 2nd-generation Hispanic immigrant children. Results show significant, positive main effects of ECE and SES on English proficiency. However, results also reveal that the association between ECE and English proficiency differs by SES. Among 1st- and 2nd-generation Hispanic children from very low-SES households, the odds of being proficient in English for children who attended ECE is more than double the odds for children who did not attend ECE. In contrast, the association between ECE and English proficiency for higher SES children did not reach significance. Additional analyses reveal similar patterns for income but not maternal education. Practice or Policy: These results highlight the need for ECE programs that target the poorest Hispanic immigrant children.