For 2 decades, science teachers have been encouraged to orient their instruction around the practices of scientific inquiry; however, it is unclear whether teachers have the knowledge and skills to do so. In this study, we draw upon data from the 2011 National Assessment of Educational Progress to examine the extent to which eighth-grade science teachers' educational backgrounds are related to using inquiry-oriented instruction. We focus on aspects of teachers' educational backgrounds that are most frequently used by teacher education programs and state licensing agencies as proxies for teachers' content knowledge and professional preparation to teach science. We find that teachers' educational backgrounds, especially in science and engineering disciplines and science education, are associated with differences in the extent to which teachers engage in inquiry-oriented instruction, regardless of teaching experience. Findings suggest that teachers' educational backgrounds are relevant considerations as standards-based efforts to reform science instruction in middle-level classrooms move forward.