Based on archival research and ethnographic fieldwork in northeast Argentine province of Formosa, this dissertation examines the dynamics of popular mobilization and demobilization in cases of environmental contamination. Drawing on the sweeping advance of genetically modified (GM) soybeans in Argentina I reconstruct and compare different responses of peasants to agrochemical exposures to address the following question: Why, when facing an environmental onslaught, do people from the same community sometimes react by organizing transgressive protests while at other times failing to engage in disruptive action? The analytic goal is to explain the ways in which people think, feel, and act (or fail to act) when affected by environmental problems. I argue that this variation in responses to environmental damage can be accounted for by observing three dimensions: first, the authorities' denial/acknowledgement of the environmental damage; second, activists' participation in political networks; and third, people's views on environmental damage and the effectiveness of collective action. The dissertation's Introduction elaborates the overarching argument, presents definitions of key concepts, and details the methods used for the analyses. Chapter Two discusses the relevant literatures relating to social movements, patronage politics, and biotechnology in agriculture. Chapter Three provides the background on neoliberalization processes in Argentina, the expansion of GM crops, the history of Formosa and its peasant organizations, and the communities of Monte Azul, Moreno, and Bermellon. Chapter Four presents a diachronic comparison of transgressive mobilization and demobilization in Monte Azul. Chapter Five presents a synchronic comparison of transgressive mobilization in Moreno and contained mobilization in Bermellon. Chapter Six presents an ethnography of the everyday life of a peasant organization showing the interconnections between social movements and patronage politics, two political phenomena which are usually understood as distinct and opposing spheres. The Conclusion summarizes the dissertation's main arguments and findings, and proposes avenues for future research.