With about 60 percent of American children under age 5 spending part of their day in care outside the home, many policymakers seem to be jumping on the early childhood education bandwagon. Most states now fund or are creating preschool programs, many have developed learning standards for young children, and it is becoming widely accepted that high-quality early childhood education enhances school readiness and reduces racial and ethnic achievement gaps. Policy makers need to know where to direct their efforts before students can fully reap the rewards of early education. In designing high-quality early childhood programs, many important choices need to be made, such as deciding whether to provide universal care or to target services to the most vulnerable youngsters; how much time is needed in preschool (i.e., what age to start, how many years it should last, and whether it should be full day or half day); and what kind of follow-up might be needed in "regular school." The first step in making such decisions is knowing what makes a program "high quality."