This book is about the prospect of a social turn in the field of second language acquisition (SLA), in particular, that part of SLA that is devoted to the input-interaction-output (IIO) model. The book is intended to critically examine some of the basic notions and assumptions that underpin this model and to suggest a more interdisciplinary and socially informed approach to SLA research. The book asserts that the IIO approach does not take sociolinguistic considerations into account, suggesting that a more interdisciplinary and socially informed approach to SLA research is in order. It draws on recent work in sociolinguistics and SLA research influenced by sociolinguistic and sociohistorical approaches to language and language learning, demonstrating a need to broaden the horizons of SLA. Following a short history of SLA, the book examines the field by focusing on the meaning of each word in SLA (second, language, and acquisition). It rigorously examines the IIO model, demonstrating how it might positively benefit by utilizing a more socially informed and interdisciplinary manner. Finally, the book offers some thoughts on the future direction of SLA research. (Contains approximately 400 references.) (SM)