The purpose of this study was to investigate teachers' perceptions of levels of implementation and levels of effectiveness in improving student learning of Professional Learning Communities (PLCs) in Kanawha County Schools. This study also sought to determine differences in levels of implementation and effectiveness for five selected independent variables and examined the relationship between levels of implementation and levels of effectiveness. Finally, this study described teachers' suggestions to enhance their PLC experience and identified challenges that hindered the implementation of PLCs. A researcher-developed survey was used to collect data. The study population consisted of 1,788 teachers. Respondents (N=1,017) were from 44 elementary schools, 14 middle schools, and eight high schools. Teachers reported PLC implementation levels as some of the time and most of the time and judged them to be somewhat effective and effective in improving student learning. Levels of implementation were significantly different based on organizational structure, grade/developmental level, and sex. Levels of effectiveness were significantly different based on grade/developmental level. The correlation between levels of implementation and levels of effectiveness was significant and moderately strong. Allowing schools to select content for PLC meetings and more effective team construction were the strategies most often suggested to enhance the PLC experience. The most frequently listed challenges to implementation of PLCs were negative attitude, pre-decided content and inadequate training. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]