The book covers a research gap in Conversation Analysis and Interactional Linguistics about co-production and the emerge of syntactical structures in multiperson talk-in-interaction. The findings have theoretical and empirical implications for our understandings of the relationship between turns and clauses, and for studies on collaborative turns in spoken Italian. From the research, grammar emerges as a pragmatic matter, situated in the interactional settings that participants co-build. The book innovatively introduces collaborative grammar, a set of grammatic, embodied, prosodic and interactional resources that participants mobilise in accountable ways, becoming a visible product in interaction: the epiphenomenon of their collaborative achievement.