The Mambila social structure, unlike the majority of those studied in West Africa, is characterized by the presence of kinship groups with corporate functions which are not unilineal. All members of these units claim descent from a common male ancestor or his sibling, but descent may be traced through males, females, and in some cases through links including both sexes. A knowledge of the changes in both the traditional and present marriage practices is essential for obtaining an understanding of this kinship system. Changes in the two principal Mambila kinship groups—the memin and the man—over the past three or four decades will also be analysed.