Over the last several decades, participation in center-based preschool programs has become much more common, and public support for these programs has grown dramatically. Nevertheless, participation remains far from universal, and policies vary across states, as well as across options such as private childcare, preschools, Head Start, and state pre-K. Since policymakers typically have more alternatives than money, they face key questions about the value of preschool education, whom it should serve or subsidize, and which program designs are best. This brief reviews the research regarding the short- and long-term effects of preschool education on young children’s learning and development.