From 1929 to 1937, Chinese reformers in the Mass Education Movement attempted to transform pigs and pig breeding in Dingxian, Hebei, through the importation of an American breed of pig and its hybridization with local pigs. This episode provides a case study for the investigation of the roles played in scientific work by local Chinese materials and practices on one hand and Western scientific principles and methods on the other. Reformers were conscious that the wholesale importation and implementation of Western science had failed China in the past and suspected that it would fail again. Their chief concern was that the new pig should raise production levels but still "suit local conditions." But "conditions" and "methods" do not play equal roles in science, and reformers did not require the scientific methods of pig breeding to negotiate with local methods. Despite their attention to local conditions, the reformers thus assumed that modern, Western science was universal in nature and that it could and should be applied universally, replacing local knowledge and practices. Keywords: agricultural reform, breeding, China, pigs, science.