We compare the effects of early childhood education on adult criminal behavior across time periods, using administrative crime data that provide significant precision advantages over existing work. We find that improvements in early childhood education led to large (20 percent) reductions in later criminal behavior, reductions that far exceed those implied by estimates of test score gains in prior studies. While the benefits generated account for a large portion of the costs of the education provided, we find substantial relative gains from the targeting of funds to high-poverty areas and areas without existing access to subsidized care. (author abstract)