The Handbook of Second Language Acquisition presents an integrated discussion of key, and sometimes controversial, issues in second language acquisition (SLA) research. Written by 27 of the worlds 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.