As school districts' professional development trends shift to meet annual budget requirements, it is worthy to explore the benefits of professional learning communities as they are a potential means for job-embedded professional development. As an advocate for professional learning, Hirsh (2009) stated that every teacher should engage in professional learning at their school as part of their workday. A strong commitment by the school leader to develop professional learning communities is necessary (Hord, 1997). The primary purpose of this study was to explore principals' and teachers' perceptions of the effects of professional learning communities and to investigate ways to improve professional learning communities. This research employed a case study methodology. The investigation combined an online questionnaire and telephone interviews. This decision was directed by the purpose of the study: to investigate the phenomenon of professional learning communities. The researcher explored the experiences and perceptions of elementary teachers and principals who participate in professional learning communities. The researcher administered the Professional Learning Communities Assessment-Revised to elementary teachers participating in professional learning communities and conducted interviews with the elementary principals. The prominent features of the research results were noted in the teachers' responses on the online questionnaire. There were no differences in perceptions that were dependent on whether teachers taught grades K-2 or grades 3-5 or whether teachers had 4 or more years of experience or 1 to 3 years of experience in a professional learning community. The differences in perceptions were dependent on the teacher's school and the years of teaching experience. The principals shared the importance of the initial training at the DuFour's conference as well as the report form they created for teachers to report back to them after meetings. They agreed that professional learning communities help teachers focus on instruction; however, they emphasized the need for time, professional development and other supports to initially implement them in a school. This research study has shown that professional learning communities are dependent on shared and supportive leadership as the principal creates the conditions to ensure their success. The findings suggest that professional learning communities have the potential to help teachers learn from one another when appropriate structures are in place to support collaborative discussions focused on student learning. Future research in the areas of school culture, leadership styles, online learning alternatives as well as the need for ongoing, job-embedded professional development may enhance the principal's leadership role of professional learning communities. [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.]