The purpose of this study was to explore secondary English teachers' perceptions of the benefits and challenges of professional learning communities (PLCs), with particular focus on what they considered to be characteristics of effective PLCs. Through a qualitative study in grounded theory using individual interviews among a subgroup of ten secondary English teachers, various factors distinguishing successful professional learning communities emerged. Examining what these teachers have learned from personal experience created a better understanding of what high schools can do to improve the effectiveness of teacher collaboration and, consequently, the academic success of high school students. The study determined that there are common factors that help make professional learning communities more successful. [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.]