Given the proper focus, professional learning communities (PLCs) are the most effective form of professional development. Current literature shows no other mode hitting as close to the mark of entrusting teachers to manage what they are teaching, how they are teaching, where they are intervening, where they are challenging, and why all this is all taking place. As simple and noble as this rationale sounds for schools adapting a PLC model, there are significant hurdles that consistently arise to threaten the implementation of such promising practice. The simple, thus, becomes complex for a variety reasons, many rooted in emotion rather than logic. This work identifies many of these predictable problems as they appear in high schools and suggestions practices used in the four schools studied for overcoming these hurdles. In addition to the practical, the work also documents change theories that support a new system of solutions. The work focuses on answering three questions: (1) What are the benchmarks (essential structures and cultural indicators) that define a PLC? (2) What significant hurdles do high schools face in the PLC transformation process? (3) What change processes are effective in overcoming these obstacles? In my decade of PLC work, the vast majority of PLC promoters have taken on this challenge for one simple purpose--to increase learning for students by encouraging efficacy in staff. Hoping to encourage the spread of this cause, this work is dedicated to helping PLC builders, particularly those working at the most challenging level of high school, to enter their work with their eyes opened to predictable hazards and their mind prepared with probable solutions. [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.]