Book excerpt: Now in its fifth edition, the award-winning How Languages are Learned has established itself as an indispensable introduction to research in language acquisition and its relationship with classroom practice. Patsy Lightbown and Nina Spada have worked for over four decades in second language research and education. They are highly respected worldwide for making theory and research about language learning accessible and relevant to classroom teaching. This widely acclaimed book remains essential reading for second language teachers. • Updated content highlights the latest research into second language learning and its relevance to classroom practice • Activities and questions for reflection personalize content and support critical thinking • Chapter summaries, discussion questions, weblinks and supplementary activities are available online at www.oup.com/elt/teacher/hlal