The concentrations of major and trace elements of potsherds from the Iron Age and 1st century at archaeological sites in Portugal were studied by instrumental neutron activation analysis to define local centers of manufacture and trade. The concentrations were used to calculate distance matrices which were then subjected to cluster analysis to group the sherds according to similarity in composition. The major clusters corresponded to sites at Conimbriga, Santo Olaia, and Lisbon and some of the sherds showed patterns suggesting trade relations among sites. -- AATA