This paper outlines patterns of kin classi® cation and marriage in seven regions of Australia. It considers the implications of differences in those patterns for such features of economy and society as levels of polygyny, the structure and dynamics of country groups, the form of exchange networks and, very brie ̄ y, cosmologies and the roles of religious leaders. The analysis demonstrates certain associations between modes of kin classi® cation and organisational forms such as moieties. Finally, the paper draws conclusions about the environmental and institutional conditions for differences in `levels’ of polygynous marriage, as well as their political and economic consequences