Responses to the imposition of market-oriented economic policies have varied. This article asks two questions: (1) How can we better understand when marketization will or will not prompt resistance? And (2) when people do mobilize, why are some movements broad-based while others draw on particular segments of society? The author argues that these questions can best be answered by focusing not only on the political contexts and resources available to potential social movements, but also on what is perceived to be at stake during marketization. These perceptions influence mobilization processes and the kinds of groups available for mobilization. When people understand markets as threatening to material wellbeing, as well as to widely shared community relationships, understandings, and commitments, heightened feelings of group belonging can contribute to broad-based mobilization. The author develops this argument through analysis of the broad-based, widespread movement that emerged to protest water privatization in Cochabamba, Bolivia, in 1999 and 2000. In the context of a history of agriculture, irrigation, drought, and conflict, water helped to produce and reproduce imagined communities of nation, region, and ethnic group, as well as quotidian communities revolving around the routine production and consumption of water. These meanings help to explain the dynamics of the resistance that emerged.