This report summarizes the available evidence on the impact of selected early childhood education (ECE) programs. Understanding and quantifying the outcomes likely to result from a given intervention is an essential part of planning a pay for success (PFS) project. In the first part of this report, we give an overview of the outcomes typically targeted by early childhood interventions. In part two, we summarize the evidence on early childhood education, focusing specifically on preschool and prekindergarten programs. In the third and final part, we discuss the implications for stakeholders considering a PFS model to support early childhood programs in their own communities. (author abstract)