Non-governmental organizations (NGOs) operate in the Brazilian Amazon, mobilizing actors and resources to promote sustainability, mainly by supporting the construction of alternative farming systems. The main efforts are focused on reducing deforestation by means of agroforestry projects, which are introduced as alternatives to extensive livestock farming. This study analyzes the strategies adopted by the Amazonian Institute of Conservation and Sustainable Development and the World Wide Fund for Nature to engage farmers and other actors in their programs. The study was conducted in Apuí, one of the target municipalities of public policies aimed at combating deforestation. The findings reveal that these NGOs adapt their strategies throughout time in face of expressive institutional complexity in local and macro spheres. Acting as “institutional entrepreneurs,” NGOs have changed their discourses from an eminently preservationist focus to one that is more adapted to the economic concerns of local actors and connected to their moral and cultural norms, which also imply a reframing of “sustainability” through a scientific discourse that embodies a more technocratic approach to forest conservation.