This report summarizes the findings of a literature review conducted as part of the Assessing the Implementation and Cost of High-Quality ECE (ECE-ICHQ) project funded by the Office of Planning, Research and Evaluation within the Administration for Children and Families at the U.S. Department of Health and Human Services. The project's goal is to create a technically sound and feasible instrument that will provide consistent, systematic measures of the implementation and costs of education and care in center-based settings that serve children from birth to age 5. The ultimate measures will inform research, policy, and practice by improving understanding of variations in what centers do to support quality, their associated costs, and how resources for ECE may be better aligned with expectations for quality. We reviewed the literature and research syntheses in three areas--ECE quality, implementation science, and ECE costs--to create a conceptual framework that will guide measurement development. (author abstract)