The purpose of this brief is to provide guidance to states as they build comprehensive statewide assessment systems. The brief specifically focuses on child assessment within the context of an overall birth to age 8 early childhood assessment system. Other reports have focused on assessment as it relates to classroom and program quality (e.g., National Research Council, 2008). The brief begins with a set of guiding principles related to assessment of young children birth through grade 3. Next, it describes four types of child assessments, including their purposes, recommended assessment procedures, and commonly used assessment tools and resources. The brief concludes with recommendations for states as they develop their comprehensive assessment systems. (author abstract)