In 2013, preschool education received more attention in the media and public policy circles than it has for some time, in part because of a series of high-profile proposals to expand access to quality pre-K. The scientific basis for these proposed expansions of quality pre-K is impressive. This paper brings to bear the full weight of the evidence to address the following questions: (1) What does "all" the evidence say about effective preschool education and long-term cognitive benefits?; (2) What are the estimated effects of state and local pre-K programs in more recent years?; (3) Is Head Start ineffective?; (4) Can government improve the quality of public preschool education?; and (5) If states expand pre-K with temporary federal matching funds, what happens to state education budgets when that federal money is not available? Given the answers to these questions it seems self-evident that local, state, and federal governments should expand access to quality pre-K and other enhancements of early education, especially for children in low-income families.