The Handbook of Second Language Acquisition presents an integrated discussion of key, and sometimes controversial, issues in second language acquisition research. Discusses the biological and cognitive underpinnings of SLA, mechanisms, processes, and constraints on SLA, the level of ultimate attainment, research methods, and the status of SLA as a cognitive science. Includes contributions from twenty-seven of the world's leading scholars. Provides an invaluable resource for all students and scholars of human cognition, including those in linguistics, psychology, applied linguistics, ESL, foreign languages, and cognitive science.