Concerned with how new schooling structures, once implemented, will remain in place, this paper reviews findings of the International School Improvement Project (ISIP) about institutionalization and suggests their application to educational restructuring results. According to the ISIP study, indicators of complete institutionalization include acceptance by relevant actors, routinization of the change, widespread usage, firmly expected continuation, and legitimacy or invisibility of the change. The restructuring literature largely sidesteps the topic of institutionalization. A more general literature review reveals institutionalization's dependence on high-quality innovations, local and external contexts, and the change process itself. A case study analysis discloses other key factors, such as policy-level confirmation, vision-building, external and internal support, school leader maintenance, staff ownership, and embedment. Institutionalization is not monolithically determined, but is ensured by a configuration of key aspects. The ISIP results suggest action implications for those desiring to institutionalize change in schools: applying alternative frames (managed change, cultural change, assimilation, and conflict); achieving district-school congruence; providing extra energy resources; allowing sufficient time; developing a clear, shared vision; envisioning implementation as prefigured institutionalization; managing transition effectively; stressing personal and organizational learning; routinizing internal support; and avoiding staleness. (21 references) (MLH)