Large numbers of U.S. students lack proficiency in science, and students from different ethnic and socioeconomic groups show disparities in science achievement.2 Science knowledge and skills are important for both academic and workplace success, and a variety of interventions have been developed to improve student science achievement. "Project-Based Inquiry Science™" is a science curriculum for students in grades 6-8 with approximately 13 independent instructional units, each covering a topic in life science, earth science, or physical science. In each 8- to 10-week unit, teachers first orient students to a "big question" or "big challenge" that frames the unit, such as how to improve air quality in the local community, and then guide students through a series of activities to answer a set of scripted smaller questions on the path to answering the big question (such as "What is air?", "What are pollutants, and how do they get in air?", and "How can air quality be improved?"). Students collaborate in small groups to identify relevant concepts, conduct hands-on explorations or investigations, read relevant informational texts, reflect on what they have learned, and apply new knowledge toward answering the big question. This What Works Clearinghouse (WWC) report, part of the WWC's Primary Science topic area, examines research on the effects of "Project-Based Inquiry Science™" on science achievement of students in grades 6-8. No studies of "Project-Based Inquiry Science™" that fall within the scope of the Primary Science review protocol meet WWC standards. Because no studies meet WWC standards, the WWC is unable to draw any conclusions at this time about the effectiveness of "Project-Based Inquiry Science™" on science achievement.