The Handbook of Second Language Acquisition presents an integrated discussion of key, and sometimes controversial, issues in second language acquisition (SLA) research. Written by twenty-seven of the world's leading scholars, the chapters reflect the diversity and technicality that have come to characterize SLA research. Topics discussed include 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. This volume is an invaluable resource for all students and scholars of human cognition, including those in linguistics, psychology, applied linguistics, ESL, foreign languages, and cognitive science.