Agricultural cooperatives in Ecuador have experienced varied levels of success as well as increased difficulty staying together in the past 20 years. In addition, a trend towards greater concentration of landholdings and corresponding increases in inequality erodes land reforms positive impact on the equitable distribution of land, albeit limited. For example, migrant laborers seek work with the new, large palmito and African palm plantations. These in-migrants are becoming more numerous than the original land-seeking pioneers who colonized northwest Ecuador's Las Golondrinas area 20 -30 years ago.|Research linking the areas of migration and social structure has neglected the implications of migration for the design and effectiveness of cooperative social relations, including the development of agricultural cooperatives. Drawing on quantitative and qualitative data about migration streams, villages' social networks and the social networks of agricultural cooperatives in the Las Golondrinas colonization zone of northwest Ecuador, this research demonstrates the dynamics of three processes. First, migration affects the social relations involved in colonists' economic activities, with high mobility nurturing the tendency to trust fellow villagers based on similarity of their socioeconomic status, especially in the more central town of a regional economic system. Second, cultural similarities and the cohort effects of in-migration dampen this tendency, thus altering the conditions under which capital accumulation detracts from or improves formal and informal cooperation. Third, this specifically is the case for agricultural cooperatives; at the beginning, cooperatives may be held together by wealth differences because wealthy members take on disproportionate costs (and benefits). To succeed in the long term, however, the cooperatives must rely on in-group mechanisms for creating trust or a sense of shared fate.