This book offers a comprehensive study of language development. The contributors, all well-known psychologists, represent a very broad range of theoretical persuasion. Each chapter summarises research on a major problem and relates results to fundamental questions about how children acquire language. Among the issues treated are the role of input in acquisition, the processes of underlying lexical and semantic development, the implications of cross-linguistic research for acquisition theory, the pros and cons of functionalist approaches to language learning and the psychological consequences of a major new formal theory of language learning. In their long and thoughtful introduction, the editors demonstrate the complementarity of studies focused on seemingly separate problems and identify apparent trends, both theoretical and methodological. Taken together, these chapters provide an entry point into an increasingly complex field for the growing number of researchers and students in psychology and linguistics whose work requires an understanding of the child's first steps in language.