Networked improvement communities (NICs) mark a promising approach to address the challenges of sustaining school reform. Whereas NICs are intended to help scale and sustain reforms, there is little evidence on how this works, as few NICs have existed long enough to be described over time. This study uses social network theory to understand what happened after the removal of external supports for a NIC regarding the sustainability of the improvement efforts as well as the NIC itself. We use social network data and interviews conducted with about 70 school and district leaders within the NIC to examine changes in the organizational infrastructure that maintained or changed network features. Our findings indicate that, upon the withdrawal of external supports, the network constricted, though core network features were maintained. However, changes to the infrastructure, such as a reliance on teacher-leaders and a focus on school-level empowerment, present challenges to the long-term sustainability of the NIC.