Farmer field schools (FFSs) emerged in response to the gap left by the worldwide decline in agricultural extension services. With time, this methodology has been adapted to specific rural contexts to solve problems related to the sustainability of peasant-farming systems. In this study we draw upon empirical data regarding the peasant-farming system in the Nicaraguan highlands to evaluate whether FFSs have helped communities improve the sustainability of their systems and the food security of their residents using socioeconomic, environmental, and food and nutrition security (FNS) indicators. In order to appreciate the long-term impact, we studied three communities where FFSs were implemented eight, five, and three years ago, respectively, and we included participants and nonparticipants from each community. We found that FFSs have a gradual impact, as there are significant differences between participants and nonparticipants, and it is the community that first implemented FFSs that scores highest. The impact of FFSs is broad and long lasting for indicators related to participation, access to basic services, and conservation of natural resources. Finally, this paper provides evidence that FFSs have the potential to empower farmers; however, more attention needs to be paid to critical indicators like production costs and the use of external inputs in order to scale up their potential in the future.