This quantitative, nonexperimental research study focused on discovering the impact of inquiry-based instruction on the science achievement of rural Georgia fifth-grade students as measured by the Georgia Milestones Assessment System (GMAS), a criterion referenced test. Inquiry-based instruction is a teaching method that combines the natural curiosity of students with the scientific method to enhance the development of critical thinking skills. The study also examined the perceptions of teachers regarding their use and beliefs about inquiry-based science instruction. The data collection included two years of fifth-grade Georgia Milestones science achievement results. Findings revealed that the group of students who received inquiry-based instruction during the 2017-18 academic year demonstrated significantly higher achievement as measured by GMAS than the group of students who were taught using the traditional direct instruction method in 2016-17. Survey responses of teacher perceptions of inquiry-based instruction indicated that most teacher participants believed that students were more engaged in inquiry-based learning and also noted improved achievement of students with disabilities. The majority of teacher participants reported that they were able to manage the change from direct instruction to inquiry-based instruction but requested additional professional development opportunities. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]