After decades of archaeological excavations, legacy collections present us with vast reservoirs of untapped research potential. By studying Ceramic Age (ca. 500 bc–ad 600) Caribbean pottery from Hacienda Grande (Puerto Rico) and Salt River (St. Croix), this exploratory study devised a method for the use of nondestructive geochemical analyses (portable X-ray fluorescence) on large ceramic collections to research various aspects of cultural interaction, such as trade, exchange, social networks, and mobility. A set of ceramic information was divided into multiple variables to test the geochemical data for patterns of variability due to vessel use, production techniques, or provenance of raw materials. The results indicate that the potters from Hacienda Grande most likely used only one local clay source, but applied different production and finishing techniques in relation to the vessel function; whereas, the ceramics found in Salt River indicate at least two clay sources or different tempers, yet little variation in finishing techniques. The results obtained in this study support the image of self-sufficient communities that maintained a close source-to-site distance in ceramic production and consumption. Furthermore, the observed similarities between islands point to a shared cultural package as the result of knowledge transmission through interaction, rather than transportation of pottery between sites and islands.