In order to identify the main agroecosystems, their limiting factors and adequate technological options, participatory approaches, such as community ranking, were used in a micro-hydrological basin in Central Oaxaca, Mexico. This area is characterized by small farm size (1-2 ha), low input agriculture and low standards of living. The results of a pretested survey were presented at community meetings and were subjected to discussion to rank the problems found in order of importance. Overall, the main production constraints were: low soil fertility, insect pests and plant diseases, lack of rain and soil erosion. After field evaluations of several sustainable technologies, the following was found: a) organic mulching can reduce soil erosion, weeds and conserve soil moisture, b) intercropped green manures with maize could be a mean to improve soil fertility while still allowing producing this staple crop, c) composting of crop residues with weeds and farmyard manure was also promoted amongst the peasants, but only a few of them adopted this practice due mostly to high labor requirements and d) even though it is an expensive technology, the use of floating row covers to produce tomatoes and hot peppers was quickly adopted by the peasants. It was concluded that the best way to convince the peasants to adopt a technological innovation is to show them that it works under their own circumstances.