Book excerpt: Engaging Children in Vast Early America examines the often overlooked roles that children played in moments of contact between Indigenous groups, Europeans, and Africans in North and South America over the course of the seventeenth through nineteenth centuries. Adulthood is the default lens through which most of history is examined. This is because so few historians analyze the age or life stage of those they study. As a result, people of the past are often assumed to be adults when their actions or experiences align more closely with what modern society deems “adultlike.” Many of these “assumed adults,” however, were agentive children. This collaborative collection is the first of its kind to invite experts in the field of Vast Early America to engage with the history of childhood and youth. The result is nine innovative essays that expand our understanding of childhood and agentive children but also of empire and everyday life in Vast Early America. This accessible text is a unique resource for undergraduate courses in childhood and youth history, family history, and early American history.