This work deals with the law relating to families and family relationships in Lagos and the southern Regions of the Federation of Nigeria, including the proposed Mid-West Region. It is primarily concerned with customary law; hut as statute law and principles of English law have made many incursions into the sphere of customary law, most of the topics covered have had to be treated on a comparative basis. A unified treatment, rather than a separate investigation of the laws of each ethnic group in turn, is adopted because there is happily a remarkable degree of uniformity in these laws. But any local variations that do exist are indicated in the appropriate places; and where, as in intestate succession and prohibited degrees of relationship, there are no common principles, the ethnic groups are dealt with individually or in groups falling within well defined patterns. The thesis is in two parts. Part One is concerned with the extended family. Among the items discussed here are the family as a corporate socio-legal entity; the position of family heads and family councils in contemporary society; the concept of family property and the rights therein of family members considered as individuals and disintegration of the family. Part Two is concerned with the elementary family or household. Chapters V-VII deal with the formation of family units through marriage, while Chapter XIII discusses additions thereto through adoption and guardianship. The two types of customary law marriage and the four essential requirements for a valid marriage are here investigated, the legal effect of the omission of any one of these requirements being also discussed. Chapters VIII-X analyse the law of husband and wife - including a wife's membership of her husband's extented family; her right to his name, his citizenship, his domicil and the matrimonial home. The next two chapters deal with the law of parent and child - including illegitimacy (which does exist as a status under customary law), legitimation by subsequent marriage and by acknowledgment, the affiliation of a child to one of three possible families, and the vicarious liability of parents. Finally, Chapter XIV discusses the dissolution of marital relations - the point being made that whereas a wife's death brings a marriage to an end for all purposes, a husband's death leaves intact the wife's status as a married woman for a number of purposes