Drawing on data from a range of contexts, including classrooms, pharmacy consultations, tutoring sessions, and video-game playing, and a range of languages including English, German, French, Danish and Icelandic, the studies in this volume address challenges suggested by these questions: What kinds of interactional resources do L2 users draw on to participate competently and creatively in their L2 encounters? And how useful is conversation analysis in capturing the specific development of individuals’ interactional competencies in specific practices across time? Rather than treating participants in L2 interactions as deficient speakers, the book begins with the assumption that those who interact using a second language possess interactional competencies. The studies set out to identify what these competencies are and how they change across time. By doing so, they address some of the difficult and yet unresolved issues that arise when it comes to comparing actions or practices across different moments in time.