Dissecting twenty years of educational politics in our nation’s largest cities, offers one of the clearest assessments of school reform as it has played out in our recent history. Joseph P. McDonald and his colleagues evaluate the half-billion-dollar Annenberg Challenge—launched in 1994—alongside other large-scale reform efforts that have taken place in New York, Chicago, Philadelphia, and the San Francisco Bay Area. They look deeply at what school reform really is, how it works, how it fails, and what differences it can make nonetheless. McDonald and his colleagues lay out several interrelated ideas in what they call a theory of action space. Frequently education policy gets so ambitious that implementing it becomes a near impossibility. Action space, however, is what takes shape when talented educators, leaders, and reformers guide the social capital of civic leaders and the financial capital of governments, foundations, corporations, and other backers toward true results. Exploring these extraordinary collaborations through their lifespans and their influences on future efforts, the authors provide political hope—that reform efforts can work, and that our schools can be made better.