The conversion of large urban high schools into small, focused learning centers is gaining currency as an education reform strategy. This publication provides guidelines, along with guiding questions, for those considering such a conversion. The first section explores the structural, organizational, and political challenges involved in converting large high schools into identifiable, autonomous learning communities. It begins with a discussion of the advantages of "small." It continues with an examination of the experiences of some large schools that have broken into small learning communities but have failed to produce the desired results. From these efforts have emerged eight strategies, which the guide presents in detail. The second section of the guide explores the challenges that emerge once a school has reorganized into small units. It looks at how these units stay focused on the combination of effective learning principles and practices that "small" makes possible. It presents examples of routines and best practices from successful small schools, alternative schools, and youth-development programs. Finally, the guide presents a tool, "the five Cs," for blending youth development approaches with contextual and authentic learning to create effective learning environments. (References are included in 11 footnotes.) (WFA)