This book presents one of the first attempts at developing a precise, grammatically rooted, theory of conversation motivated by data from real conversations. The theory has descriptive reach from the micro-conversational - e.g. self-repair at the word level - to macro-level phenomena such asmulti-party conversation and the characterization of distinct conversational genres. It draws on extensive corpus studies of the British National Corpus, on evidence from language acquisition, and on computer simulations of language evolution. The theory provides accounts of the opening, middlegame, and closing stages of conversation. It also offers a new perspective on traditional semantic concerns such as quanitifcation and anaphora. The Interactive Stance challenges orthodox views of grammar by aruging that, unless we wish to excluse from analysis a large body of frequently occurrringwords and constructions, the right way to construe grammar is as a system that characterizes types of talk in interaction.