This study draws from 4 years of qualitative case study data to describe how programmatic and district factors interacted to affect reform sustainability in two school districts--one urban and the other suburban. These districts have been implementing a reform developed by the National Network of Partnership Schools (NNPS) for over a decade. NNPS assists schools, districts, and state departments of education to develop comprehensive programs of school, family, and community partnerships. Findings suggest that reform characteristics, specifically the evidence base, costs, and flexibility of the NNPS reform, and district leadership, specifically district leaders' reform knowledge, professional influence, and reform focus converged to explain, in part, the case districts' success in sustaining the reform. Implications of these findings for reform developers and leaders are discussed. (Contains 1 table.)