The study of “usage” has constituted a major line of second language learning research for decades now. The concept of usage, however, can be defined and studied in many different ways.In this comprehensive, forward-looking text, international scholars from a variety of perspectives review and critically examine current conceptualizations of usage, learning, and their connections in the field of second language acquisition (SLA). Bringing these diverse perspectives into conversation, Kevin McManus synthesizes the state of the art to set the agenda for new directions in theory-building and empirical SLA research.This text will be an invaluable resource to students and researchers in SLA, applied linguistics, psychology and cognitive science, education, and related areas.