One of the greatest challenges to comprehensive school reform (CSR) is sustaining reform over a period long enough to produce substantial effects. This article highlights the importance of studying sustainability as well as the importance of being clear about what is being sustained, distinguishing between a sustained reform relationship and sustained implementation of a reform. This study examined a sample of 395 urban, disadvantaged, low-achieving elementary and middle schools using CSR in 2001-2002 and found that nearly 1/3 of these CSR schools ended their relationships with their model developers by the end of 2003-2004. However, the remaining 2/3 of schools successfully sustained a reform relationship for more than 3 years--in some cases for more than a decade. The results of Analysis 1 indicate that 11 risk factors for discontinuing a reform relationship operate in combination to dispose schools toward dropping their CSR affiliation. Analysis 2 shows that although dropping a CSR model affiliation is significantly related to decreases in implementation fidelity, the magnitude of the decrease is relatively small. In many urban, disadvantaged, low-achieving schools, the influence of CSR models can live beyond the formal discontinuation of the reform relationship.