Prior to entering kindergarten, most young children in the United States today participate in childcare or educational programs provided by someone other than a family member. These high rates of participation have been facilitated by rapid increases in public investment. Given the heightened public investment in Early Childhood Education and Care (ECEC) programs and the clear push towards expanding program access, it is surprising how little we know about the current availability of ECEC and its effects. The highly decentralized nature of the ECEC sector and the related absence of a comprehensive source of data about ECEC providers have left policy-makers with a fragmented understanding about the availability of programs. This project is designed both to enhance our understanding of ECEC availability in the United States and to shed light on the relationship between the expansion of ECEC and the educational opportunities and outcomes for children.