The purpose of the multiple-site study was to explore educator's perceptions of the Professional Learning Communities (PLCs) that had been operating in three school districts using in-depth interviews. The goal of this research was to describe from the educator's perspective what they perceived, thought and observed about the PLCs functioning in their school building, and whether or not the PLCs had any noticeable effect on professional development, school improvement efforts, and student achievement in their building. Educators were also asked the question of why they thought that PLCs were effective. This multiple-site case study is important to Nebraska educators because many school districts have initiated a variety of forms of PLCs in their school buildings or districts. School districts that have implemented PLCs reported positive perceptions from educators about increased opportunities for professional development and school improvement in their districts. This study involved three school districts in Nebraska that had been operating PLCs for a minimum of three years. The researcher found that educators in all three districts had positive perceptions about the effects of PLCs in the areas of professional development, school improvement, and student achievement. While the perceptions of educators indicated student achievement was likely improved through the use of PLCs, there was no hard evidence to confirm those perceptions. [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.]