This work reviews recent research on the role of interaction in second language acquisition (SLA) studies. It argues that an ethnomethodological approach to conversation analysis can provide valuable conceptual and methodological insights into how mundane conversation and institutional varieties of talk may potentially function as resources for SLA. More specifically, the book is divided into three parts. In part 1, the author begins by defining key terms and providing an overview of current issues in SLA. He then develops a rationale for the need to reconceptualize our understanding of the processes of SLA as a set of conversational practices that are grounded in the behaviours that participants display to each other (and therefore also to analysts) as they engage in talk-in-interaction. In part 2, the author builds on this rationale by discussing the three constituent elements of interactional competence: the sequential organization of talk, turn-taking and repair in different speech exchange systems. Finally, in part 3, the author applies the methodology of CA to analyze two similar sets of empirical data to show how this methodology may be used to demonstrate both successful and unsuccessful attempts at language learning, at least in the short term.