This report describes initial findings from a study of middle school science curriculum materials that were designed to promote learning as called for by the Next Generation Science Standards (NGSS). WestEd led an independent randomized controlled trial to evaluate the efficacy of the NGSS-designed Amplify Science Middle School (ASMS) curriculum. This study examined the impact of the materials in 7th grade classrooms across three school districts. Schools were randomly assigned to one of two groups: an intervention group in which teachers implemented ASMS and a comparison group in which teachers implemented their regular curricular units. Science teachers in both groups implemented instruction that aimed for the same NGSS performance expectations. Hierarchical linear regression modeling was used to analyze the impact of the curriculum on student learning outcomes in physical science, as measured by an assessment aligned to NGSS performance expectations. Initial findings show promise that the ASMS curriculum can be used to support next generation science learning. The main result was that students in intervention classrooms significantly outperformed students in comparison classrooms. This study is among the first rigorous studies of widely available curriculum materials for the NGSS.