To learn more about the use of ongoing assessment in early education, the Office of Planning, Research & Evaluation funded a project in fall 2012 to explore how teachers use children's data to individualize instruction for each child. The project's goals were to (1) develop a conceptual framework of ECE teachers' use of ongoing child assessment to individualize instruction and (2) create a measurement tool to examine this process. One component of the project is a review of the literature on ongoing assessment in early childhood. This review aims to provide insight on whether and how teachers use ongoing assessments to tailor their instruction. It also is intended to help develop criteria for determining the quality of teachers' ongoing assessment practices. This brief summarizes the findings from the literature review and offers important next steps. (author abstract)