Parents, policymakers, business leaders, and the general public increasingly recognize the importance of the first few years in the life of a child for promoting healthy physical, emotional, social, and intellectual development. Yet many children face deficiencies in the years leading up to school entry in terms of emotional support, intellectual stimulation, or access to resources — due to low income or other factors — that can impede their ability to develop to their fullest potential. As part of a recent study to examine the role of early childhood interventions, RAND researchers identified what is known from the research literature about the number of children at risk of school failure and the consequences for their performance in school and subsequent life outcomes. We summarize those findings here.