This contract supported the development of a literature review, conceptual model, and tool designed to measure teachers' use of child assessments for individualizing instruction to support optimal development in early childhood settings. The literature review summarized the research on child assessment and individualized instruction and includes a conceptual model as a means of articulating the theoretical relations between key constructs underlying the process. A measurement plan derived from the literature review outlined key constructs, defined relevant terms and mechanisms, and proposed options for measurement that would be feasible in a variety of early childhood contexts. As a result of this work as well as two iterative rounds of pretesting, the Examining Data Informing Teaching (EDIT) measure was developed.