Regional exchange, consisting primarily of transactions among groups that are not adjacent or in regular contact, is described here for the Pacific coast of Costa Rica, during the period A.C. 1200--1550. The Gulf of Nicoya area was the center of an active regional exchange system, which has been detected archaeologically through research on the gulf islands. This system is described in terms of its role in relation to local and long-distance exchange, both in providing goods and in establishing and maintaining social relations over some distance. Regional trade, rather than either intersite exchange among neighboring settlements or long-distance trade in exotic items, is seen as the network that supplied the inhabitants of a site with the majority of needed goods from food to tools and sumptuary items.