The socioeconomic study was conducted at the southern zone of Costa Rica, in the district of Pejibaye, located in Perez Zeledón, through an inquiry of 80 producers aleatorily chosen. The information was obtained on May, 1999. About 84% are landowners, with productive units of an average of 14.5 ha. Most of the basic grains producers diversify with others farming activities, such as spoonflower, coffee and pasture. It was determined that the level of diversification increases with the size of the productive units. Also, within the subsystem of basic grains, most of them diversify it in combination with corn and bean. Ninety percent of the producers plant corn during summer time (December to February), with an average area of 2.5 ha and with an average production of 1.9 t/ha. Regarding bean, the main crop comes on wintertime (May to August) with an average area of 3 ha, and a yield of de 0.6 t/ha. For both grains, the tendency goes to the reduction of areas and product. For corn, as well as for the bean, most of the crop goes for market, and in general, that is to say that the production of both grains have an income-producing result in terms of cost/benefit, being more profitable the bean activity. During the latter years, the climatic instabilities have affected the output of basic grains, which has made the producers to turn into other productive activities. The producers have began to use some strategies in order to encounter these effects, such as the use of coverings, and some other cultural and agronomic practices.