This dissertation evaluated the implementation of professional learning communities in a large suburban school district in North Carolina. The presence of shared and supportive leadership, shared values and vision, collective learning and application, shared personal practice, supportive conditions for relationships, and supportive conditions for structures are all attributes that were assessed to determine the degree of implementation. A quantitative and qualitative program evaluation was conducted using the CIPP evaluation model to determine the degree of implementation of professional learning communities and whether or not the implementation has had an impact on student achievement based on state end of course test results. The CIPP model of program evaluation is a systematic process to evaluate the context, input, process and product of a particular program to determine the effectiveness of the program. Teacher members of the Algebra I, English 9, and Biology professional learning communities at each of the six high schools were asked to complete the "Professional Learning Communities Assessment-Revised" survey. The researcher also requested to observe a sample of professional learning community meetings with these teachers to determine whether or not there is evidence that certain characteristics of the professional learning community concept exist. Interviews were conducted with each of the 6 principals, the assistant superintendent of secondary education and the facilitator of professional development. [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.]