For decades, policymakers and researchers have struggled to understand the reasons that schools in disadvantaged contexts have relatively more trouble responding successfully to reform demands. This analysis extends theory regarding the challenges of school change in disadvantaged contexts by illustrating how the internal resources that schools rely on to respond to external policy demands can be affected by the social contexts in which they are embedded. The article draws on data from a study of five high poverty high schools' responses to the pressures of Texas' high stakes accountability system. The case study data illustrate how a school's social context can precipitate instability in some schools and relative stability in others, how organizational stability in turn can affect schools' organizational social capital, and how organizational social capital can influence schools' ability to respond to external policy demands. (Contains 3 notes, 3 tables, and 1 figure.)