The Early and Middle Formative periods in Mesoamerica (1500-500 BC) witnessed many sig-nificant changes from the Preceramic period in population growth, architecture, settlement patterns, and artifact categories. One of the most striking changes, however, was in the enormously expanded volume of material, both raw and finished, traveling between cultural regions and between environmental zones. Interregional movement of pottery, obsidian, jade, turquoise, iron pigments, iron ores, mica, mollusk shell, turtle shell, fish and stingray spines, shark teeth, and other commodities often reached impressive proportions. Many of these items were of ritual use, and, as pointed out by Drennan (nd), probably reflected an increasing role for rituals of sanctification on the part of Formative peoples. Others were “utilitarian” in nature, although the line between utilitarian and nonutilitarian is often hazy. Even ritual paraphernalia, insofar as it strengthened the integration of Formative communities and tightened the links between families who also exchanged foodstuffs and subsistence items, could be considered to have a utilitarian aspect.-In this paper, the term “exchange” has bee used in preference to “trade,” in much the same manner that Sahlins (1965) used it in his article,“On the Sociology of Primitive Exchange.” The term “trade” has been used in so many different contexts—many of them associated with state Societies, and the kinds of formal trade engaged in by Western states—that we prefer not to use it. The kind of “primitive exchange” described by Sahlins is more appropriate for the level of sociopolitical evolution we assume, on the basis of all available archeological evidence, to have characterized the Early and the Middle Formative periods. In such societies (corresponding roughly to the ideal types originally defined by Service [1962] as “tribes” and “chiefdoms” and by Fried [1967] as “egalitarian” and “rank” societies, respectively), exchange frequently takes the form of gift-giving, with the unstated assumption that the gift will be reciprocated at Some time in the future, though not necessarily with the same commodity. Equivalences between commodities are generally not fixed, nor are the rates of exchange standard, although Sahlins (1972) has shown that participants do have ideas about the relative values of the goods exchanged. Much long-distance “primitive exchange” is facilitated by having the participants set up a fictive kin relationship or “trade partnership,” and the usual means of escalating the volume of exchange is to produce an extraordinarily lavish gift requiring an extraordinary reciprocation. Apart from Sahlins' work, superb models for the operation of primitive exchange systems can be found in Rappa-port’s (1967) work on the Maring of New Guinea, Harding’s (1967) work on the Siassi Islanders, and Leach's (1964) work on the