This paper discusses the importance of research in community participation as part of primary health care. The research component was carried out in the northern mountains of Oaxaca, including the diagnosis and correlation between the migratory process from an area with high demographic expulsion and the nutritional and health conditions of six communities in Oaxaca. The action component included the implementation of resolutive actions in the communities with the highest migration. These actions were: diagnosis and nutritional surveillance; parasite infestation surveillance and treatment with anti-helminthic plants; unconventional edible plants; and nutritional education (through community participation theatre), among others. In general terms, the results of the diagnosis provided insights into the variety of forms of migration, ranging from the disorganization of the community to more intelligent collective strategies for survival. Regarding the nutritional condition of preschoolers, it was found that, while 85 per cent of those living in the mountains were undernourished, undernourishment practically does not exist in the migrant families in Mexico City. It can be concluded that positive results were obtained from those actions largely due to the active participation of the communities and to the health auxiliaries trained in the fields of nutrition, health and ecology. Finally, the need to establish research-action plans with a higher level of interdisciplinary participation is emphasized. The primary goal of these plans would be to improve the living standards of people who are both the object and subject of research and not to reduce the findings to "mere numbers", because, as it is so often the case, when this occurs, the perspective of the communities' reality is lost.