Nested in a complex environment of expectations, regulations, professional standards, and historical traditions, schools are the object of many influences. The main question of this paper is: To what extent and under what conditions do external agents help schools develop intellectual quality and strong professional communities? The paper examines data from the Center on Organization and Restructuring of Schools' (CORS') School Restructuring Study, which focused on 24 schools undergoing restructuring. The findings provide insights about the relationship between school structures and the schools' professional cultures. Three forms of assistance by external agents were found to have the potential to promote intellectual quality and professional community: sustained schoolwide staff development; standard-setting aimed at learning of high intellectual quality; and deregulation. By itself an external agent could not successfully transform an unfocused, fragmented school into one characterized by intellectual quality and professional community. Those schools whose culture already predisposed them to consider issues of intellectual quality and professional community found productive ways to use the resources and opportunities offered by external agents. In short, successful reform depended on interaction between positive aspects of culture and structure. However, independent developers, districts, states, and parents provided important technical assistance, funding, and political support. Each of the 24 restructuring schools experienced some positive influence from external agents. The most successful schools had basic cultural features that combined with structural autonomy to allow them to flourish at the margins of their educational systems. (Contains three references and four endnotes.) (LMI)