Childhood multilingualism has become a norm rather than an exception. This is the first handbook to survey state-of-the-art research on the uniqueness of early multilingual development in children growing up with more than two languages in contact. It provides in-depth accounts of the complexity and dynamics of early multilingualism by internationally renowned scholars who have researched typologically different languages in different continents. Chapters are divided into six thematic areas, following the trajectory, environment and conditions underlying the incipient and early stages of multilingual children's language development. The many facets of childhood multilingualism are approached from a range of perspectives, showcasing not only the challenges of multilingual education and child-rearing but also the richness in linguistic and cognitive development of these children from infancy to early schooling. It is essential reading for anyone interested in deepening their understanding of the multiple aspects of multilingualism, seen through the unique prism of children.