A key principle of inquiry-based science education is that the process of inquiry must include opportunities for the exploration of questions and ideas, as well as reasoning with ideas and evidence. Teaching and learning Science therefore involves teachers managing a discourse that supports inquiry and students engaging in talk that facilitates their learning. This article outlines the role of talk in science learning, distinguishes between types of discourse, argues that types of talk need to be matched to phases of scientific inquiry, and develops a pedagogical framework that supports a discourse of inquiry. (Contains 4 figures.)