What allows children to acquire language so effortlessly, with such speed, and with such amazing accuracy? Capitalizing on the most recent developments in linguistics and cognitive psychology, this volume sheds new light on the what, why, and how of the child’s ability to acquire one or more languages. The Handbook is one of a kind in a number of respects. It includes state-of-the-art treatments of acquisition from a variety of theoretical viewpoints ranging from functionalist approaches and the implications of the creolization of languages for the study of acquisition to the relevance of Chomsky’s Minimalist Program. It contains overviews of the acquisition of all components of linguistic structure, treats the acquisition of the sign languages of the deaf, and discusses the specific problems of bilingual acquisition.