Large investments are made in curriculum materials with the goal of supporting science education reform. However, relatively little evidence is available about what features of curriculum materials really matter to impact student and teacher learning. To address this need, the current study examined curriculum features associated with student and teacher outcomes. We reviewed sample curriculum materials and documentation reporting on the instructional outcomes of 51 research-based K-12 science curriculum materials. Our findings reveal that teacher supports, rather than student supports, had positive impacts on both student and teacher outcomes. Specifically, positive student outcomes were associated with curriculum materials with a larger scope and with materials that provide teachers with information about students' ideas and recommended instructional strategies. Positive teacher outcomes were associated with the presence of information about targeted standards and recommended instructional strategies. Relatively fewer studies reported on teacher outcomes, and evidence about other dimensions of curriculum materials impact (e.g., spread, sustainability) was difficult to find. Overall, these results reveal the broad importance of embedding teacher supports and ensuring sufficient scope of content across coordinated curriculum units to support the development of conceptual understanding over time. Implications for the design of new curriculum materials and further research are discussed.