Ongoing child assessment is increasingly viewed as a tool for informing and individualizing instruction in early childhood, yet little is known about how ongoing child assessment is implemented at the classroom or the programmatic level. This literature review focuses on how teachers use ongoing assessment and adjust instructional practices and content to better meet the individual strengths, needs, and interests of young children. We identified four important issues in the literature in ongoing assessment in early childhood: (1) many teachers do not consistently collect ongoing assessment data, nor do they use it for instruction and individualization; (2) barriers to using data include lack of pedagogical content knowledge and knowledge about how to conduct assessments and interpret data; (3) teachers want more training and professional development in this area; and (4) more needs to be known about how to support the successful implementation of ongoing child assessment. (author abstract)