Based on a case study of Ghanaian cocoa farmers who attended farmer field schools (FFS), this paper explores the impact of the FFS methodology on farmers' technical knowledge, experimentation, knowledge diffusion, group formation and social skills as a way of assessing whether the relatively high costs associated with the method is justified. We carried out focus group discussions for exploratory purposes and a formal survey of 70 FFS graduates and 70 non-FFS farmers. The superior knowledge test scores of FFS graduates relative to non-FFS farmers demonstrates the effectiveness of the method for communicating complex knowledge and information to farmers in a way that allows them to understand it and retain it. An assessment of changes in farmers' experimental capacity showed variable results. On the one hand, a significant proportion of FFS graduates applied some of the principles and practices learned to solve productivity problems with other crops, while others did not perceive any change in their experimentation behaviour. Significantly, an important skill farmers learned in the FFS was making observations on cocoa trees and the wider ecosystem as the basis for decision-making. The case study confirmed that FFS strengthened social cohesion among cocoa farmers and enhanced individual social skills by creating new networks for knowledge exchange and support, promoting group formation and improving farmers' confidence and ability to work more effectively in groups. The paper concludes by recommending areas for improving FFS and highlights how strengthening human and social capital in cocoa growing communities can serve as a springboard for broader development activities. (Contains 6 tables.)