This is one of the few studies that estimates the effects of type of childhood care on academic achievement at higher grade levels by linking day care registers and educational registers. We use entire birth cohorts of ethnic Danish children, enrolled in either center based day care or family day care at age 2. Exploiting variation across municipalities in guaranteed access to center based care as an instrument for type of care our results show that center based day care improves grades in Danish language in the final year of compulsory school with around 0.2 standard deviations. (author abstract)