The article describes a systematic review of 109 studies using the data-informed decision-making framework to understand the sources of assessment data and the main purposes for assessment use among early childhood educators. Findings revealed assessment use is driven by the purposes of measuring and monitoring children's learning and development, informing instructional next steps, communicating with caregivers, and identifying students for early intervention. Standardized assessments of multiple domains, teacher observations, student work samples, and student background information emerged as key sources that inform decision-making. We noted several factors that likely influence teachers' assessment use to consider in preparing teachers for DIDM. We describe these considerations in terms of structural-, teacher-, child development, and assessment tool-related influences. Early childhood assessment use is different from primary or secondary contexts that largely inform the DIDM literature. We conclude with implications for preparing educators' DIDM by presenting six skillsets to foster their ability to engage in critical thinking about standardized assessments, engage in intentional observation, generate high-quality data, engage caregivers as consumers and sources of data, use multiple data sources for early intervention identification, and advocate against accountability-driven DIDM.