American Educational Research Journal Spring 2004, Vol. 41, No. 1, pp. 115-157 Inequality in Preschool Education and School Readiness. Katherine A. Magnuson Columbia University Marcia K. Meyers University of Washington ChristopherJ. Ruhm University of North Carolina, Greensboro Jane Waldfogel Columbia University Attendance in U.S. preschools has risen substantially in recent decades, but gaps in enrollment between children from advantaged and disadvantaged families remain. Using data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999, we analyze the effect ofparticipation in child care and early education on children's school readiness as measured by early reading and math skills in kindergarten andfirstgrade. Wefind that cbildren who attended a center or school-based preschoolprogram in the year before school entry perform better on assessments of reading and math skills upon beginning kindergarten, after controlling for a host of family background and otherfactors that might be associated with selection into early education programs and relatively high academic skills. This advan- tagepersistswhen children'sskills are measured in thespring of kindergarten andfirst grade, and children who attended early education programs are also less likely to be retained in kindergarten. In most instances, the effects are largestfor disadvantaged groups, raising the possibility thatfiolicies pro- moting preschool enrollment of children from disadvantagedfamilies might help to narrow the school readiness gap. . KEY;oRDs: child care, early childhood education, inequality, school readiness. the share of children attending early education programs has risen dra- Tmatically in recent years in the United States. In 2001; 66% of all 4-year- olds were enrolled in a center or school-based preschool program, up from 23% 30 years earlier (National Center for Education Statistics [NCES], 2003; U.S. Bureau of the Census, 1970). However, attendance among children from low-income families and with less educated parents remains relatively low. For example, children whose mothers have a college degree are nearly twice