Traditional agrarian societies tend to develop corporate groups as important structural components. These groups are ascriptive and are formed on such bases as kinship, occupation and ethnicity among others. They pervade many areas of life and are significant to both the identity and activity of the individual. Traditional Latin American society, however, was not characterized by such groups. Both prehispanic corporate kin groups and medieval Spanish groups such as the gremio disintegrated after the Conquest. Traditional Latin American society is characterized by flexible ego-centered networks, a strong ideological emphasis on an individualistic self-concept and a preference for individual autonomy in activity. Despite this lack of emphasis on collectivities, recent urbanization in Latin America has been characterized by widespread proliferation of voluntary associations as corporate groups. This process is less an outgrowth of traditional patterns or a spontaneous response to new needs than it is a result of the diffusion of Euro-American group models. Because of a general lack of experience with collectivities, certain kinds of activity and function are emphasized in Latin American voluntary associations while others are less successful. Participation varies according to class, age, sex and nationality. More data is needed to test the hypothesis that while voluntary associations follow modernization in Latin America they are weaker there than elsewhere in such aspects as proportion of population affiliated, importance of group membership to the individual and longevity of groups. Such weakness might be related to the lack of experience with groups in traditional society.