In this chapter, we argue that given the critical importance of stimulating early childhood experiences, the growing evidence that high-quality early education improves children's school readiness and leads to better education outcomes, the current high enrollment rates of children of families with means in formal preschool, and the market-level failures to provide such opportunities to families across the income spectrum, preschool policy has moved beyond a tipping point. To ensure that all children have an equal playing field for succeeding in school and reaching their fullest potential, the United States must extend access to high-quality preschool to all three- and four-year-old children. (author abstract)