ABSTRACT THE PROCESS OF ADOPTION OF SMALL SCALE IRRIGATION IN RURAL MEXICO Case studies about the process of production in agriculture in four Mexican communities with small scale irrigation are presented. Peasantry is viewed as a sui-generis system of production with a rationality which guides productive decisions for the obtention of a culturally defined subsistence level, which cannot be measured by the common factor of money. Peasant economic units are seen as subordinated parts of a dominant socio-economic system. Relations of domination are explained by the concept of articulation, which is manifested by the asymmetry of exchanges with the larger system in detriment of the peasants. Exchange imply transference of economic surplus of peasants to the rest of society by means of the intervention of agents and institutions, the mechanisms of operation of which tend to increase polarization between peasant producers and between agriculture and other sections of society. The dependent development of national economy tends to reproduce polarization and structural need. Irrigation was considered as an innovation to be induced in the process of production. The adoption was not only a function of the advantages for more profitable production. The issue of subsistence was a central parameter in the adoption of new agricultural projects. The decision to adopt surpassed the limits of peasant rationality because the articulation of peasant economies with external factors set the limits within which they could manage their resources. Such restrictions were partly offset by the communitarian norms that regulated exchanges between peasant economic units. A comparative analysis of case studies was made; two main concepts were taken: “managing logic” that lies behind the productive decisions and “control” that contextual factors exert upon peasant production. Field information was structured along those concepts and their intervening variables; then, four types of economies were extracted: infra-subsistence , surplus, appointed and peasant economy of decomposition. The communities studied evolved to one of the four types. In the process, irrigation was a co-producer; however, it has not played the role expected by the government. In general, surplus generated by irrigated crops has been extracted from the communities, therefore it has not been used for their own development.