A large body of evidence suggests that public provision of quality preschool education can be an effective way to enhance the lives of children in disadvantaged families and to decrease inequality in educational, economic, and social outcomes (for an overview, see Yoshikawa et al. 2013). However, there are few well-documented examples of large-scale successes along with some well-known failures (Barnett 2011a). We maintain that most public programs fail to invest sufficiently in the necessary quality and intensity to reproduce either the experiences or outcomes of successful models. We describe and analyze the outcomes of New Jersey's Abbott preschool system as a counterexample for the consequences of a sufficient investment. In doing so, we clarify the nature of the public investment required if preschool is to have a substantial effect on inequality. (author abstract)