After decades of reform efforts in public school systems in the United States, there is minimal student achievement progress to measure. This article addresses the ongoing challenges and complexities of the sustainability of educational reform through a review of the literature and the proposal of a Sustainability Index as a metric to benchmark the sustainability status of a reform. Highlighting a 2-year study in an urban school system in California, this work analyzes the navigation of an educational reform initiative using a Sustainability Index as a tool for reform planning. The results of the study identify a number of potent implications for reformers, school leaders and university preparation programs. (Contains 1 table and 2 figures.)