The ultimate goal of teacher professional development is to improve student achievement by improving teacher practices. To that end, the literature and research supports the development of professional learning communities as one of the most effective ways to accomplish that goal. Therefore, the research questions addressed in this study were: (a) Are schools in Mississippi using professional learning communities? (b) To what degree does the principal rate his or her school is functioning as a professional learning community as measured by the "School Professional Staff as Learning Community instrument" (Hord, 1996)? (c) Is there a relationship between student achievement as measured by the 2011-2012 Mississippi Quality Distribution Index and the degree to which the school is functioning as a professional learning community?, and (d) Is there a relationship between the frequency of professional learning community meetings and student achievement as measured by the 2011-2012 Mississippi Quality Distribution Index? The study used descriptive statistics to compile demographic information as reported by elementary school, middle school, and high school principals from across Mississippi. A Pearson correlation was calculated to determine if a meaningful relationship existed between student achievement and the degree schools functioned as learning communities, and a correlation was calculated to determine if a relationship existed between student achievement and the degree of frequency of professional learning community meetings. The findings from the study determined a significant statistical relationship did not exist in degree of function and student achievement or in frequency of meetings and student achievement. Although no significant statistical relationships were found, there were several positive findings in the study: (a) 98% of the respondents reported the use of professional learning communities in their schools; (b) Principals believe their schools function at a high level as professional learning communities; (c) The study indicated schools met regularly and even frequently for the purpose of collaboration; (d) The study pointed to a conscious commitment by both principals and teachers towards working together to provide support for a collaborative learning community; and (e) The study indicated that organizing schools into productive professional learning communities is a high priority for principals. [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.]