Book excerpt: The new edition of Key Terms in Second Language Acquisition defines the key terminology within second language acquisition, and also provides accessible summaries of the key issues within this complex area of study. The final section presents a list of key readings in second language acquisition that signposts the reader towards classic articles and also provides a springboard to further study. The whole book has been updated and expanded to take into account a wider range of theories and developments since the first edition. It remains at the top of its game. The text is accessibly written, with complicated terms and concepts explained in an easy to understand way. Key Terms in Second Language Acquisition is an essential resource for students.