Project-based learning (PjBL) instruction is an inquiry-based method that is beneficial to student achievement and their exploration of 21st-century learning skills, but there is a gap in the literature about how Grades 6 to 8 teachers feel about PjBL and its implementation. The research problem was science teachers in the United States were not consistently implementing project-based learning strategies as an instructional method to support students' learning and academic achievement. The purpose of this study was to explore Grades 6 to 8 science teachers' perceptions about the implementation of project-based learning instruction to support science education. The conceptual framework for this qualitative study was Dewey's constructivist learning theory. The research questions addressed Grades 6 to 8 science teachers' perceptions of their experiences when implementing project-based learning during science instruction. Data were gathered for this basic qualitative study through semistructured interviews from eight participants who taught middle grades science and used project-based learning instruction for 5 years or more. Data were analyzed through coding and thematic analysis. Overall, Grade 6 to 8 science teachers perceived that PjBL had a positive effect on student engagement, participation, and motivation during science instruction. The findings showed that teachers believe they needed more time to plan, collaborate, and practice the PjBL strategy. The results from this study contributed to positive social change by suggesting best practices for the PjBL framework. On the other hand, the data also revealed barriers related to the implementation of project-based learning in science classrooms, which require attention for teachers to consistently engage students in hands-on learning and promote student success in inquiry-based fields. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]