A closely analyzed exposition of how children acquire language that explores the receptive and productive abilities of children in all core areas of language--phonology, morphology, syntax and semantics. Readers will acquire the fundamental knowledge and skill not only to interpret primary literature but to approach their own research with sophistication. While the descriptive facts that are currently available on first language acquisition are central to the book, its emphasis on methodology and explanation distinguishes this text from others. The various ways in which research is conducted is discussed in detail, as well as the strengths and weaknesses of different approaches, leading to new perspectives on key theoretical issues.