That human communities cannot be treated a mosaic of isolated cultural permutations has been realized for some time. Rather, they are embedded in larger systems of relations which increasingly have become the focus of anthropological study in their own right. To date, the main work in this area is by political economists who have attempted to elucidate the interrelations of local economies and polities, usually out of an interest in the effects of capitalist penetration. Cultural or ritual interactions, though, have been rather less the objects of regional studies (cf. Werbner 1977), partly perhaps because symbol and ideology are often viewed little more than reflection or legitimation of social relations. Needless to say, this situation has begun to change with the recognition in cultural anthropology and archaeology that the expansion of cultural and symbolic forms can be a ready point of departure for cultural integration, political expansion, and settlement centralization (e.g., Keatinge 1981; Knauft 1985; Lindstrom 1984; Schwartz 1963). Unfortunately, the processes by which cultural and symbolic forms spread are still poorly understood. The societies of the Sepik Basin of Papua New Guinea thus have a special ethnographic relevance to the problem because they engage in an import and export of ritual and artistic culture that reaches intensities almost unparalleled in the nonindustrial world (Barlow 1985; Errington and Gewertz 1986; Harrison 1987; Lipset 1985; Lutkehaus 1985; Lutkehaus and Roscoe 1987; Mead 1938:162; Tuzin 1984:4). This interaction assumes two major forms. Among the societies of the Sepik River and Coast, it is particularly pronounced a kind of trade in discrete cultural and symbolic items (spells, cult sacra, house-styles, stone monoliths, and so on) that are treated though they were transactable goods as more than just meaningful or expressive forms, but political and economic resources, values to be bought, sold, exchanged, stolen, hoarded, and so forthH (Harrison 1987:493). Among the cultures in the southern foothills of the Torricelli-Prince Alexander ranges, however, a form appears that has received rather less analytical attention and which is perhaps best described a large-scale cultural transfer or assimilation. Although this transfer sometimes entails economic or political transactions, it is not so much a trade a gradual diffusion of cultural complexes across entire societies on a scale usually large enough to precipitate further, substantial cultural changes. In this paper, I attempt to elucidate some of the motivational and processual underpinnings of this sort of phenomenon by examining a relatively recent instance: the importation by several Yangoru Boiken villages of the spectacular long yam cult commonly associated with the Abelam. I attempt to show that the