In anthropological studies of African societies a recurring problem of analysis centres on the relationship between descent groupings and territorial units. A categorical distinction, such as Maine advanced (1861), between kinds of societies or groups based on either descent or locality is empirically spurious (Gluckman 1971: 85). Fortes has emphasised that the problem is one ‘of assigning an order of relative weight to the various factors involved in culture and in social organization, or alternatively of devising methods for describing and analyzing a configuration of factors so as to show precisely how they interact with one another’ (1953:25). Other writers have favoured this same move from reductionist either-or typologies to relativistic functional propositions, notably in analysing the modalities of descent (Lewis 1968; Goody 1969), of descent and affinity (Schneider 1968; Leach 1971), of kinship – and neighbourship (Gulliver 1971). But despite these developments, comparative analysis is still often based on crude correlations derived from an arbitrary and piecemeal codification of data (Hallpike 1971). My approach in this essay is guided by three structuralist propositions: descent and locality are (1) complementary principles, the significance of one being relative to the significance of the other, (2) mental —representations and tactical signs, rather than institutions sui generis, (3) variables within a transformational system, the system being susceptible to analysis at the level. of both organization and conceptualization.