In a policy climate driven by tests and external mandates, theories of school reform that place teachers, their knowledge, and their relationships at the heart of school improvement have garnered attention as promising alternatives. Yet little exists in print about how such theories actually work or what these approaches look like in practice. This article attempts to open up that black box by offering one example of these reform theories in action. The example derives from a study of the goals, structure, and nature of support provided within one particular network--the Middle College National Consortium (MCNC)--toward the implementation of a reform called Early College. In providing technical assistance to schools, teachers, and organizations within and outside of its membership, the MCNC network presumed that the knowledge for implementing the Early College reform, from technical details to substantive strategies for teaching, learning, and student support, inhered in the experience and expertise of veteran practitioners. The article thus describes some of the ways that the MCNC network provided assistance, development, and support for implementing Early College that depended upon the mutual sharing and building of knowledge among a network of like-minded practitioners. In so doing, it pays special attention to the role of practitioner expertise, principle-based reform, and the opportunities afforded by networks. While the paper highlights successful iterations of these theories in practice and considers the strengths of this teacher-centered approach, it also explores some of the associated challenges. (Contains 4 footnotes.)