While agroforestry is fairly recent as a research focus, the integration of forestry and other agricultural activities is a well established indigenous practice in many parts of the world. As such, it is a tested technology which can be adapted to economic and environmental development goals in order to avoid the problems of structural incompatibility often associated with the introduction of modern production techniques. Since the interactive benefits of agroforestry systems are often not immediately apparent, a holistic interpretive framework for on-farm activities such as the Farming Systems Research (FSR) methodology is necessary to understand or suggest adaptations in these systems. This paper outlines the biological contribution of trees on farms, and describes some common agroforestry systems in Costa Rica. As an example of how an FSR approach can be used in the analysis of agroforestry systems, a recent analysis of farmer motivations for participation in a fuelwood plantation project in Piedades Norte, Costa Rica, is discussed. This study revealed that farmers wished to have trees on their farms, but based the decision to plant on non-material benefits such as the protection of farmland, plants and animals from the elements, in addition to material products such as fuelwood or posts. Forestry project in the past have tended to overlook these factors in favor of commercial wood production. The paper concludes that promotion of forestry activities can be greatly facilitated through the application of the FSR methodology to better undestand farmers' motivations for planting or maintaining trees on farms, and thereby avoid the recommendation of production techniques and species which do not address immediate forestry needs of farming populations, or which conflict with other farm priorities