The popular notion of how children come to speak their first language is that their parents teach them words, then phrases, then sentences, then longer utterances. Although there is widespread agreement amongst linguists that this account is wrong, there is much less agreement as to how children really learn language. This revised edition of Ray Cattell's bestselling textbook aims to give readers the background necessary to form their own views on the debate, and includes accessible summaries of key thinkers, including Chomsky, Halliday, Karmiloff-Smith and Piaget.