In "When Reform Meets Reality," Jonathan A. Supovitz and contributors examine the qualities that make ambitious educational reforms impactful and identify common tensions that can thwart continuous improvement. Supovitz brings together educational researchers, district and school leaders, teachers, and professional development providers to reflect on the successes and stumbles of an ambitious district-wide reform effort--the Ongoing Assessment Project (OGAP), a program for mathematics education--as it was introduced and scaled up over five years in the School District of Philadelphia. Using OGAP as a lens, the volume explores larger themes of instructional reform, including the potential of new instructional approaches to improve the quality of teaching and learning, the contexts that can either support or hinder efforts to introduce meaningful pedagogical change, and how supporters can engage in ongoing, deeper implementation of reform measures at different levels of the educational system through multi-level learning. It also addresses the utility of metrics of learning and performance, including benchmark and formative assessments, that can provide the rare and sought-after evidence that correlates reform efforts with increases in student performance. The book underscores the ways in which school systems can foster sustained organizational learning. It suggests actions by which school faculty, working in conjunction with district leaders, reform developers, and staff, can cultivate a culture of inquiry to build deep ownership of ambitious instructional reforms.