In this paper, I draw on my own research among Boazi speaking peoples of the Lake Murray-Middle Fly area of the Southern Lowlands of New Guinea to argue that societies with sister-exchange marriage1 differ in critical ways from Collier and Rosaldo’s brideservice and bridewealth societies, and that it is useful to consider such societies as a third type in Collier and Rosaldo’s scheme. I also extend Collier and Rosaldo’s as well as Chowning’s positions and argue that factors such as postmarital residence patterns, the position of marriage in the life cycle, the character of affinal obligations and brothersister relations are all essential for understanding marriage as well as day-to-day marital and gender relations. As among Kove, Boazi men depend on the cooperation and compliance of women—in their case to organise sisterexchange marriages—and this dependence significantly shapes gender relations more generally.