Drawing on a systematic review of over 500 documents, this study finds that, although FFS (farm field schools) projects have changed practices and raised yields in pilot projects, they have not been effective when taken to scale. The FFS approach requires a degree of facilitation and skilled facilitators, which are difficult to sustain beyond the life of the pilot programmes. FFS typically promotes better use of pesticides, which requires hands-on experience to encourage adoption. As a result, diffusion is unlikely and has rarely occurred in practice.