LET US NOW LEAVE HISTORY ASIDE AND TURN TO SOME MORE RECENT DEVELOPMENTS in the study of the problems of kinship and social organization first opened up by Morgan. Research and scholarship, both ethnographical and theoretical, grow and ramify so vastly and swiftly in this field that no one can now hope to compass all of it with equal facility. I do not aspire to do so. My concern is not with large generalizations but with a limited number of structural parameters. It is certain mechanisms and processes of social organization and the principles that underlie them that I am interested in elucidating.