Knowing and deploying local, indigenous, or traditional knowledge has become an increasingly important instrument for the design and implementation of development and conservation initiatives in the Third World. This article explores the strategic mobilization of local knowledge through a case study of the politics of knowledge that emerges within projects aimed at the on-farm conservation of agricultural biodiversity in the Peruvian highlands. In framing traditional farmer practices and knowledge as integral to agrobiodiversity conservation, development and conservation groups take recourse to a particular construct of Andean culture. Yet tension arises between the customary delegitimization of Andean cultural traditions and the new appeals to value them, ambivalence emerges within interventionary discourse practice, and the recognition of local farmer expertise in a broader context of social hierarchy is rendered problematic. This case study of local knowledge, its mobilization and negotiation within a particular rendering of "culture," ideological differences between institutions, agricultural heterogeneity, and the agency of recipient farmer groups have broader implications for how we study the utility and value of local knowledge and "cultural essentialism" in other development and conservation contexts, including those of East Timor.