As more states have become engaged in kindergarten assessment efforts, early childhood educators and assessment experts have recommended developing such efforts within a coordinated assessment system that provides data about children's progress over time, (pre-k through grade 12), and is designed to address both educational policy and practice questions. Based on the review of current efforts, the Early Childhood Education State Assessment Collaborative's (ECEA) position on assessment of children at the start of formal schooling, typically kindergarten, is the following: Early child assessments conducted prior to, at the start of, and during kindergarten can be useful for a number of purposes "if done well." Kindergarten readiness assessments should be used to directly support children's development and academic achievement to improve educational outcomes. To do so, kindergarten readiness assessment efforts should adhere to the following principles: (1) Use multiple tools for multiple purposes; (2) Address multiple developmental domains and diverse cultural contexts; (3) Align with early learning guidelines and common core standards; (4) Collect information from multiple sources; (5) Implement in a systems-based approach; and (6) Avoid inappropriate use of assessment information, specifically including high-stakes decisions, labeling children, restricting kindergarten entry, and predicting children's future academic and life success. The rest of this paper will discuss the rationale of ECEA's position and important cautions for parents, teachers, administrators, and policymakers to consider when planning kindergarten assessment initiatives. A glossary is included. (Contains 1 table and 37 notes.)