Objective: To determine if child-care services (CCS) at a population level can reduce social inequalities in academic performance until early adolescence. Methods: A 12-year population-based prospective cohort study of families with a newborn (n = 1269). Two CCS variables were estimated: "intensity" (low, moderate, and high number of hours) and "center-based CCS type" (early onset, late onset, and never exposed to center-based CCS). Results: Children from low socioeconomic status (SES) families who received high-intensity CCS (any type), compared with those who received low-intensity CCS, had significantly better reading (standardized effect size [ES] = 0.37), writing (ES = 0.37), and mathematics (ES = 0.46) scores. Children from low-SES families who received center-based CCS, compared with those who never attended center care, had significantly better reading (ES early onset = 0.68; ES late onset = 0.37), writing (ES early onset = 0.79), and mathematics (ES early onset = 0.66; ES late onset = 0.39) scores. Furthermore, early participation in center-based CCS eliminated the differences between children of low and adequate SES on all 3 examinations (ES = -0.01, 0.13, and -0.02 for reading, writing, and mathematics, respectively). These results were obtained while controlling for a wide range of child and family variables from birth to school entry. Conclusions: Child care services (any type) can reduce the social inequalities in academic performance up to early adolescence, while early participation in center-based CCS can eliminate this inequality. CCS use, especially early participation in center-based CCS, should be strongly encouraged for children growing up in a low-SES family. (author abstract)