As we enter a new century, Americans are engaged in a serious national debate about the future of education. Much of the policy discussion about educational reform is focused on the school achievement gap between children of low-income families and other children, and on the stated goal of assuring "no child left behind." Research has attributed this gap to an array of problems including poverty and community violence (Barton, 2003), but studies of education have also shown that this gap among children tends to widen as they progress through school, with poor children receiving poorer-quality education in classrooms led by less-qualified teachers (Shields et al., 1999). In practice, a central goal of reform is to ensure that children of all ages receive the same quality of education--no matter where they live, what their economic status or racial or ethnic identity may be, or what kind of program or school their families choose for them. Growing documentation that the gap originates in the extremely variable levels of readiness with which American children enter Kindergarten (Shonkoff & Phillips, 2000), and that high-quality early care and education can help narrow this gap (Barnett, 1998; Barnett, Tarr, Lamy & Frede, 1999, 2001; Bowman, Donovan & Burns, 2001; Gormley & Phillips, 2003; Marshall et al., 2001), has led many to support high-quality, universally-available preschool programs.