This investigation studied the effects of the Multiple Literacies in Project-Based Learning science intervention on third graders' academic, social, and emotional learning. This intervention includes four science units and materials, professional learning, and post-unit assessments; features of project-based learning; three-dimensional learning (National Research Council, 2012); and the performance expectations from the Next Generation of Science Standards (NGSS Lead States, 2013). The intervention was evaluated with a cluster randomized control trial in 46 Michigan schools with 2,371 students. Results show that students who received the intervention had higher scores on a standardized science test (0.277 standard deviation) and reported higher levels of self-reflection and collaboration when involved in science activities.