In the last few years, conversation analysis (CA) studies have provided theoretical and methodological ways to specify how participants accomplish interactional competence (IC) in situ, and how evolving changes are occasioned and can be traced in situated contexts. This study aims to further expand the understanding of IC by using CA as an analytical approach to examine how pedagogical intervention reshapes student participation in an under-researched educational context: an extensive reading (ER) book club for second language (L2) learning. Much CA research on IC documents changes in learners' competence, but often without discussing what may have led to these changes. This study describes how the participants' methods of talking about books during the talking phase of the club meetings change after the facilitator encourages a new participation framework. The changes observed relate to active listenership and co-participation when one participant is telling the others about a book. By discussing how a facilitator's intervention alters students' ways of mobilizing and displaying their L2 IC, this study makes a unique contribution to CA research on IC. The study also discusses pedagogical implications for ER theory and L2 book club activities.