This accessible textbook introduces the field of child language acquisition, exploring language development from birth. Contents 1. The growth of language; 2. What is acquired?; 3. What is the problem of language acquisition?; 4. How we can construct a theory of language acquisition; 5. Brain and language development; 6. The nature of nurture; 7. How can we tell what children know?: methods for the study of language acquisition; 8. The acquisition of phonology; 9. The acquisition of syntax; 10. The acquisition of semantics; 11. On the nature of language growth; 12. Conclusions: towards an integrated theory of language acquisition.