Objectives: With over 1 million children served by the US Child Welfare system at a cost of $20 billion annually, this study examines the economic evaluation literature on interventions to improve outcomes for children at risk for and currently involved with the system, identifies areas where additional research is needed, and discusses the use of decision-analytic modeling to advance Child Welfare policy and practice. Methods: The review included 19 repositories of peer-reviewed and non-peer-reviewed "gray" literatures, including items in English published before November, 2009. Original research articles were included if they evaluated interventions based on costs and outcomes. Review articles were included to assess the relevance of these techniques over time and to highlight the increasing discussion of methods needed to undertake such research. Items were categorized by their focus on: interventions for the US Child Welfare system; primary prevention of entry into the system; and use of models to make long-term projections of costs and outcomes. Results: Searches identified 2,640 articles, with 49 ultimately included (19 reviews and 30 original research articles). Between 1988 and 2009, reviews consistently advocated economic evaluation and increasingly provided methodological guidance. 21 of the original research articles focused on Child Welfare, while 9 focused on child mental health. Of the 21 Child Welfare articles, 81% (17) focused on the US system. 47% (8/17) focused exclusively on primary prevention, though 83% of the US system, peer-reviewed articles focused exclusively on prevention (5/6). 9 of the 17 articles included empirical follow-up (mean sample size: 264 individuals; mean follow-up: 3.8 years). 10 of the 17 articles used modeling to project longer-term outcomes, but 80% of the articles using modeling were not peer-reviewed. Although 60% of modeling studies included interventions for children in the system, all peer-reviewed modeling articles focused on prevention. Conclusions: Methodological guidance for economic evaluations in Child Welfare is increasingly available. Such analyses are feasible given the availability of nationally representative data on children involved with Child Welfare and evidence-based interventions. Practice implications: Policy analyses considering the long-term costs and effects of interventions to improve Child Welfare outcomes are scarce, feasible, and urgently needed. (Contains 4 tables and 2 figures.)