Patterns of Late/Terminal Formative period (ca. 500 B.C.–A.D. 300) ceramic exchange in Oaxaca are examined through instrumental neutron activation analysis (INAA). Samples of 453 Late/Terminal Formative period sherds were submitted to the Missouri University Research Reactor for INAA to determine elemental composition. The sherds came from 20 excavated sites and two surveys in the following regions: the Valley of Oaxaca, Mixteca Alta, Mixteca Baja, lower Río Verde Valley, and Cuicatlán Cañada. Selected for the study were vessel fragments from three recognized paste categories: grayware (gris), fine brownware (café fino), and creamware (crema). We also sampled clays and sherds from known sources in four modern pottery-making towns in the Oaxaca Valley. The research adds to the INAA database for Oaxaca by identifying the chemical signatures of six source groupings that we can link to specific regions and, in two cases, to particular source zones within regions. The evidence from chemical composition and typology indicates continuity in resource use and production practices in both Atzompa and Coyotepec from pre-Hispanic into modern times. The data show that the exchange of ceramics in Late/Terminal Formative Oaxaca was multidirectional, with ceramics imported both to and from the Oaxaca Valley.