Kin Groups and Descent. Mataco society was traditionally divided into a series of wikyi', or groups (i.e., named, geographically localized and exogamous social units). Each group was regarded as a single entity, but each split into bands that varied in size according to the season. After the Chaco War, these groups developed into wikyi' categories and are now spread out over large areas. Nevertheless, it is easy to find a correlation between a concentration of wikyi' members and its traditional locality. Apart from wikyi' membership, there is little emphasis on descent. There is no descent ideology, and when a person dies, he or she is immediately cut out of the kinship system. Even his or her name is quickly ignored and sometimes tabooed.
Kinship Terminology. The system of kinship terminology is based on cognatic principles and could be classified as a variant of the Hawaiian type. Almost all kinship terms are generational and can be used in several genealogical positions. No difference is made between full siblings and first cousins. However, six core terms are specific (Ego, wife, mother, father, daughter, sister). These represent key concepts in Ego's family of orientation and that of procreation.