A primary aim of the neuropsychological revolution has been the mapping of what has come to be known as executive function (EF). This term encompasses a range of mental processes such as working memory, inhibitory control, and cognitive flexibility that, together, regulate our social behavior, and our emotional and cognitive well-being. In this book, top scientists from a variety of fields investigate executive function as it develops in early childhood. Because researchers differ in how they conceptualize basic processes and even in how they define EF itself, contributors begin by discussing comparability and replicability, key issues of primary importance to those seeking to move the field to a new level of rigor. Next, they tackle the nuts-and-bolts of the development of EF in preschoolers, including the neurobiological mechanisms and circuitry that underlie EF development as well as the role of EF in assessing risk and its counterpart, resilience. Finally, they highlight exciting new clinical applications of EF research, including the use of EF in contextualizing and assessing family risk, the impact of socioeconomic status on neurological development, and the promotion of EF development through early education programs.