This article employs multi-sited ethnography as a tool to explore the relationships among farmer seed exchange practices, intellectual property rights legislation, and biodiversity. Specifically, it investigates these issues in the historically, ecologically and culturally diverse contexts of the Costa Rican and Latvian organic agriculture movements, as these small countries negotiate their places in the economic trading blocs of the Central American Free Trade Agreement (CAFTA) and the European Union (EU), respectively. The juxtaposition of two such different cases reveals the micro-processes whereby the imposition of intellectual property rights on seeds replaces the centrality of social kin networks through which seeds are exchanged with bureaucratic transactions. This shift from exchanging seeds among kin to tracing the genetic lineage of seeds is part of a global process of commodification and control of seeds. Increasing efforts to “harmonize” intellectual property rights on seeds and plant varieties throughout the world will have profound impacts on food production, small farmer livelihoods and social networks, and agricultural biodiversity.