The primary purpose of the Measuring the Impact of Early Childhood Systems Results to Action (RTA) grant was to test the feasibility of cross-national, common indicators of early childhood wellbeing (common indicators) by conducting a pilot implementation of the indicators identified during the EC-LINC Outcomes and Metrics Learning Lab. Through this work, the RTA aimed to provide a “proof of concept” of how to construct the measurement and reporting of common indicators and, in the process, assess opportunities and challenges for ongoing indicator data collection and reporting. The secondary purpose of the RTA grant was to further the Learning Lab’s development and refinement of common measures of early childhood system performance (system performance measures). (author abstract)