Dewey (1933) provided the foundation for reflective practice in education with the notion that learning is not in the doing, but rather it is in the thinking about the doing that creates learning. Evidence is growing about the importance of reflection for improving teaching and learning practices to increase student achievement (York-Barr, et al., 2006). The professional learning community (PLC) has become the new catchphrase as schools engage in systems-change efforts for school improvement. DuFour, Eaker, and DuFour (2005) call professional learning communities the "most powerful strategy for sustained, substantive school improvement" (p.7). If reflective practice is a means by which teaching and learning improve and if professional learning communities provide a framework for system-wide school improvement, are the two interdependent? Using a mixed method, bounded case study research design, ten schools currently participating in the Missouri Professional Learning Communities Project (MO PLC) were selected for this study of the relationship between the level and extent of reflective practices and the implementation level of the professional learning communities process. Five schools previously identified as minimally implementing the PLC process and five schools identified as deeply implementing the PLC process were selected for the study. Using an online whole-staff survey and interviews with two school leaders in each school, data was collected and analyzed using a concurrent triangulation strategy. The Reflective Practice Spiral (York-Barr, 2006) provided the basis for the pre-determined themes used to code the interviews. The findings of this study suggest a relationship between the level and extent of reflective practice and the implementation level of the professional learning communities process. Certainly, findings from this study can support recommendations for future work of the MO PLC Project, as well as provide a springboard for further study of other school improvement initiatives supported by the Missouri Department of Elementary and Secondary Education. [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/en-US/products/dissertations/individuals.shtml.]