The Guarani cacicazgo played a fundamental role in the daily lives of the Jesuit missions (1609-1768). Through the comparative analysis of Santa Rosa baptismal records and a number of census records redacted for much of the 17th and 18th centuries, this article reflects on the role of cacicazgo in the missions, and studies its relationship with native kinship. The main argument is that the presence of the godfather and the affiliation of the new-born baby in the baptismal ceremony were important factors for the social organization of the missions. The first part of the article discusses the nature of the baptismal records in Europe and America. The second part introduces the detailed results of the analysis of Santa Rosa baptismal records in comparison to the census records, to determine the role of the godfather and the affiliation.