In this systematic literature review, we synthesize 48 research studies about science talk in elementary classrooms to inform the development of supports for teachers. Our findings suggest that characteristics of high-quality elementary science talk include that it (1) supports equitable student participation and engagement, (2) supports deepening of science understandings within and across activities, and (3) develops disciplinary literacy for science. Within each of these characteristics, we found patterns in instructional practices that promoted high-quality science talk, including discipline-neutral practices, such as ensuring that students feel valued as members of the classroom community, as well as science-specific strategies, such as providing students purposeful opportunities to engage in science practices like argumentation. Although these studies provide evidence that teachers can support high-quality science talk in elementary classrooms, we discuss that without a system of supports based on these findings, this type of science talk is unlikely to occur.