This study estimates the effect of farmer field schools in rural Ethiopia on income from agriculture. The farmer field schools were established in association with participatory forest management associations for forest protection funded by Japanese aid. We employ a difference-in-differences propensity score matching approach to correct for possible biases due to selection of participants. We find that by participating in the farmer field schools, agricultural households increased their real income per worker by about 60-160 US dollars in two years on average, which is equivalent to, or even more than, the average income per worker before the project. We also find evidence that the large increase in income is due to the use of new agricultural practices, such as new varieties, taught and promoted in the farmer field schools. Copyright © 2011 John Wiley & Sons, Ltd.