The Measures for Early Success Initiative aims to reimagine the landscape of early learning assessments for the millions of 3- to 5-year-olds enrolled in Pre-K, so that more equitable data can be applied to meaningfully support and strengthen early learning experiences for all young children. This document outlines design parameters for child assessments that meet these outstanding needs in the field of early childhood education. This Target Product Profile is intended to spur critical investments and innovations in the existing Pre-K assessment landscape, and support important stakeholder collaborations among Pre-K decision-makers, assessment suppliers, researchers, educators, and families with children in Pre-K to develop innovative assessment solutions. This document is designed to be sufficiently ambitious to meet the needs in the field for more equitable, scalable, and useful measures of children's skills and competencies. This document will help product development teams that wish to build new assessment tools that can address the challenges of today's assessment landscape. For institutional decision-makers that seek to adopt new child assessment tools, this document can serve to highlight important principles for evaluating and purchasing new solutions on the market that meet or exceed the thresholds for performance outlined in this document. [This document was developed with Substantial.]