The objective of this research is to explore the impact of early childcare on the following child cognitive outcomes: Bracken School Readiness assessment (age three of the child), Naming Vocabulary (ages three and five), Picture Similarity (age five), Pattern Construction (ages five and seven), Word Reading Score (age seven), and Number Skills (age seven). We utilize the Millennium Cohort Study (MCS) for the United Kingdom that provides very detailed information on several modalities of childcare as well as several child cognitive outcomes assessed by the interviewer, making the data more objective than answers provided by the child's mother or teacher. In our empirical analysis, we estimate the association between formal childcare and child cognitive outcomes, allowing the effect of formal childcare to be different for children from different family backgrounds and controlling for a large number of variables (relating to the child, the mother, the father, and the household). In a second step, we simulate how an increase in formal childcare attendance can affect inequalities across children. Our results show that childcare attendance has a positive impact on child cognitive outcomes that is stronger for children from a low socio-economic background. (author abstract)