Biodiesel production was stimulated in Brazil by the National Program for Production and Use of Biodiesel. The program has two objectives: ensuring both production and domestic consumption of biodiesel; and promoting diversification of feedstock sources, social inclusion, and regional development by generating employment and income for small rural farmers. However, despite the great potential for diversification of oilseed raw materials, soybeans make up the majority of the raw material that feeds the Brazilian biodiesel supply chain. Soybeans have two advantages: meeting the domestic demand for biodiesel; and having the most competitive prices, compared to other raw materials. Soybeans also support the social aspect of the federal program, although productive arrangements with small farmers are concentrated in the South region of Brazil. This paper characterizes the "social soybean" production chain for biodiesel production in Brazil and describes some of the competitive drivers that explain how soybeans from small farmers have been established as the main feedstock source. The paper also describes some bottlenecks and suggests actions that might address them in order to contribute to increased competitiveness of soybeans from small farmers in biodiesel production in Brazil. (C) 2018 Elsevier Ltd. All rights reserved.