An evaluation of a farmer field school (FFS) program for chili peppers was conducted to measure impacts on farmers’ knowledge of chili pepper integrated crop management (ICM) in Aceh Province, Indonesia. Chili production was selected as the target intervention topic because of its importance in Aceh's economy. Quantitative and qualitative methods were used to assess impacts of FFS; 270 FFS-graduate farmers were interviewed and eight farmer groups were surveyed. By integrating descriptive and simple statistical analyses, we measure immediate impacts of FFS, which also makes this study's methods and findings different from others in the literature. The results show that farmers’ knowledge on agricultural practices increased significantly due to FFS. In addition, in the future, farmers expected that their chili yields would increase and their pesticide use would decrease. FFS improved farmer cohesiveness and information sharing. Farmers’ knowledge of insect pests, diseases and natural enemies increased considerably, as did their awareness of pesticide-related hazards. In sum, FFS successfully delivered improved technology and enhanced knowledge to enable farmers to grow chili with sustainable practices and higher profits.