This article deals with communicative functions of laughter and smiling in the classroom studied using a conversation analytical approach. Analysing a corpus of video-recorded French first-language lessons, we show how students sequentially organise laughter and smiling, and use them to preempt, solve or assess a problematic action. We also focus on the link between laughter and smiling in this context, showing how these resources differently index seriousness of trouble. The article highlights the fact that students adapt their interactional competences (i.e. laughter and smiles) to a specific institutional context (i.e. trouble in classroom interaction). Through laughter and smiling, students display the actions they consider appropriate or inappropriate for the classroom, and produce and monitor their institutional identities moment by moment. This is an illustration of institutional adjustment of interactional competences, since knowing how and when it is appropriate to laugh and smile in an institutional context is relevant for students not only at an educational level but also for their future integration into the workforce. This study also offers pedagogical outputs for teachers' practice, since it helps them to better understand the interactional functions of students' laughter/smiles and how students thus manage troubles in learning settings.