The results of a study in Sri Lanka combined with a review of the literature provvide evidence that Farmer field Schools (FFS) can contribute to increasing farmers' skills and lowering insecticide use in rice. However, there are questions about their capacity to reach the majority of farmers and little evidence that skills learned are passed to nonparticipants or that FFS is a likely basis for sustained group activity. The results draw attention to the problems of relying on simple formulas in agricultural programs and point to inadequacies in the assessment of donor projects.