A GREAT deal of attention has been given within the literature of anthropology to the analysis of cross-cousin marriage and, more generally, exogamy. However, with a few notable exceptions (Cf. Ayoub 1957; Barth 1954; Chapple and Coon 1942), comparatively little interest has been devoted to the study of preferential patrilateral parallel cousin marriage and kin group endogamy. This is understandable when one considers that the contemporary occurrence of this practice is limited to the Arabs and their immediate Moslem neighbors, while the reverse phenomena of exogamy and cross-cousin marriage recur throughout the world. The latter is a regularity of such high order that it has demanded functional explanations. Such analyses have been so numerous and so persuasive that one may now wonder how preferential endogamy could possibly be a viable social form. This problem will form the substance of the present paper. Patrilateral parallel cousin marriage is evidently ancient in the Near East, from whence it spread during the Arab conquests to adjacent peoples through the vehicles of clientship, intermarriage, and religious conversion. Most commentators on the custom have repeated the Arab explanation that it keeps property within the family (Cf. Rosenfeld 1957; Granqvist 1931). But, as Barth notes (1954:170), this explanation is valid only when the Koranic law through which a daughter inherits half the amount received by a son is observed. This is very frequently not the case. In any event, the argument ignores the fact that the daughter of another family could well bring into the husband's group a most welcome inheritance, and we are thus able to use the same motivation to show that exogamy is a potential means of enhancing familial fortunes. Or phrased in another way, if we admit this to be an effective means of preserving the patrimony, why is it not common practice in a wider range of societies? In a recent article on father's brother's daughter marriage among the Kurds, Barth (1954:171) offers a variant explanation of the practice in his statement that it " . . . plays a prominent role in solidifying the minimal lineage as a corporate group in factional struggle." His argument runs that the paternal uncle is willing to forego the bride price in the case of the nephew, because he can thereby rely upon the latter's complete political support. We have here another means-end explanation, although this one has the merit of being predicated upon the particular structure of Kurdish society rather than upon a presumably general drive toward economic aggrandizement. Since Barth suggests the applicability of his argument to the Arab Bedouin, there are two points that should be here stressed. First, it is quite clear that at least