Since the 1990s, genetically modified (GM) agriculture has become a multi-billion dollar industry. Despite the rapid commercialization of GM crops in the United States, global controversy has slowed the adoption of the technology in developing countries. Yet, few studies have examined regulatory disputes outside of the United States and Europe. Debates in the United States and Europe focus on issues of human health and consumer choice. In other parts of the world, particularly Latin America, disputes center on the threats that GM agriculture poses to unique centers of biodiversity and food security, as well as issues related to bio-fuel expansion and the control over genetic resources and knowledge. My dissertation takes research on biotechnology in a new direction by analyzing the political process through which regulatory knowledge related to GM agriculture is negotiated, contested and reformulated. Guatemala is a key case to examine the politics of biotechnology regulation because despite strong US trade and transnational commercial interests, it is still illegal to grow biotech crops. The question becomes: what explains resistance to agricultural biotechnology? To address this issue, my dissertation focuses on three primary themes. First, I examine historical Mayan rural livelihood strategies within a context of political exclusion and state violence during the country's 36-year civil war. This history, in turn, informs a contemporary context characterized by the continued importance of subsistence-based corn production in the face of mounting rural inequality. Second, I contend that biotechnology regulatory debates in Guatemalan state institutions are integrally tied to a unique national context of corn biodiversity. I focus specifically on disputes between US-sponsored biotechnology regulations based on the principles of free trade and a more cautionary United Nations biosafety program. Third, I argue that resistance to agricultural biotechnology is bringing together diverse Guatemalan Mayan organizations until recently divided by the violence of the civil war. These organizations are deploying sophisticated cultural, economic and environmental knowledges that are effectively challenging efforts to commercialize GM agriculture. On a broader level, this study asserts that resistance to agricultural biotechnology is emblematic of broader struggles over the definition of legitimate knowledge in neoliberal development.