Since the 1980s, governments and transnational corporations from core countries led by the United States have driven a global upward ratchet of intellectual property protection. In agriculture, this has meant strengthening the rights of seed companies over the plant varieties they develop and curtailing the rights of farmers over the seeds they cultivate. Exceptionally, from the 1990s to 2013, Argentine soy growers overcame the pressures from the seed industry, guaranteeing the right to freely save seeds of proprietary varieties from their own harvests for future cultivation. Based on a comparative historical analysis of conflicts over intellectual property on seeds in Argentina, Brazil, and Paraguay from the 1990s to 2013, this study suggests that a successful mobilization of knowledge-users in struggles over intellectual property depends on (1) the organizational stability of their political representation, (2) the coordination between the organizations that represent them, (3) the existence of independent channels for the representation of knowledge-users most sensitive to royalty payments, and (4) their ability to produce a public discourse capable of drawing support from a broad coalition.