Written in 1978, this book is arguably the first and only systematic approach to the indigenous social organization of South American Gran Chaco. Geographically speaking the Chaco is a semi-arid central South American plain, some one million square kilometers in size, that since the end of XIXth century encompasses portions of northern Argentina, Bolivia, and Paraguay. From its first edition this book has been used by those who have studied Chaco indigenous peoples, and several investigations on the area have followed its conclusions on ethnographic sociology. The research is based both on ethnographic fieldwork and revision of historical sources, and it seeks to analyse the various historical categories that described the traditional societies of the region. It reviews the forms that these societies have adopted, the residential units, the locality patterns, the indigenous ideas concerning descent, kinship terminologies and the exogamy mechanisms that gave substance to the marriage alliance web. It also contains two lexical appendices with fieldwork material that reproduce the native kin terms and the bereavement terminologies in several languages of the area.