This letter formally transmits the attached briefing in response to GAO’s mandate included in the Child Care and Development Block Grant Act (CCDBG) of 2014 (see enclosure I). The CCDBG Act of 2014 included a provision for GAO to review every 2 years the extent of participation in the Child Care and Development Fund (CCDF) program across states. This program is one of the primary sources of federal funding for assisting low-income families with child care while they are working, looking for jobs, or participating in education and training activities. On November 18, 2020, we provided the briefing to staff of your committees to satisfy the mandate. Our briefing described 1) what is known about the number of children eligible for federal child care subsidies and the extent to which they receive them, including by state; 2) what is known about the age and family income of children eligible for federal child care subsidies compared to children who receive them; and 3) what is known about how states manage their waiting lists. (author abstract)