Back in the 1940s, the segmentary lineage theory proposed by E. Evans-Pritchard and M. Fortes was one of the basic pillars of anthropology in the study of stateless societies. However, archaeological research, which cannot access the formal analysis of kinship by its very epistemological foundations, was sidelined in the theoretical development of the segmentary model. Kinship studies have been losing relevance progressively in Anthropology as a determining factor in the identification of the essential components on which the political and social structure of a society is based. The current reconsideration of kinship anthropology has led to a revised vision of segmentary societies based on the work of E. Durkheim, allowing archaeology to be incorporated in anthropological reflection. Accordingly, this chapter focuses on the theoretical characterisation of the segmentary model as a valid tool for archaeological research on Iron Age societies, taking the castros society in north-western Iberia by way of example.