The current study, involving 219 teachers and 15,292 students, examined the relationship between teacher participation in a sustained professional development intervention designed to improve the quantity and quality of guided inquiry-based instruction in middle school science classrooms and subsequent student academic growth. Utilizing a quasi-experimental design, the growth scores of students of participating and non-participating teachers were compared to a benchmark measure established by a virtual comparison group (VCG) of similarly matched students. The results indicate that for all three MAP tests (Scientific Practices, Science Concepts, Science Composite) the students of participating teachers had significantly higher than expected growth relative to the VCG when compared to students of non-participants. In addition, students of teachers who participated in the PD intervention consistently exceeded the growth expectations of the benchmark VCG by up to 82%. This study supports prior research findings that inquiry-based instruction helps improve students' achievement relative to scientific practices and also provides evidence of increasing student conceptual knowledge.