Book excerpt: The Routledge Encyclopedia of Second Language Acquisition offers a user-friendly, authoritative survey of terms and constructs that are important to understanding research in second language acquisition (SLA) and its applications. The Encyclopedia is designed for use as a reference tool by students, researchers, teachers and professionals with an interest in SLA. The Encyclopedia has the following features: • 252 alphabetized entries written in an accessible style, including cross references to other related entries in the Encyclopedia and suggestions for further reading • Among these, 9 survey entries that cover the foundational areas of SLA in detail: Development in SLA, Discourse and Pragmatics in SLA, Individual Differences in SLA, Instructed SLA, Language and the Lexicon in SLA, Measuring and Researching SLA, Psycholingustics of SLA, Social and Sociocultural Approaches to SLA, Theoretical Constructs in SLA. • The rest of the entries cover all the major subdisciplines, methodologies and concepts of SLA, from “Accommodation” to the “ZISA project.” Written by an international team of specialists, the Routledge Encyclopedia of Second Language Acquisition is an invaluable resource for students and researchers with an academic interest in SLA.