The archaeological records from A.D. 500–1000 have been instructive for learning about cultural identity-formation process or ethnogenesis in Pacific Oceania. Such processes must have occurred during all time periods, but the centuries just prior to A.D. 1000 supported the immediate proximate contexts for the societies that became abundantly documented in the post-A.D. 1000 records and furthermore linked strongly with rich ethnohistorical knowledge. The period of A.D. 500–1000 involved transitions in artifact inventories and housing formats, loss of pottery-making traditions in some but not all places, and perhaps shifting contexts of community-level events and feasting behaviors. These processes would result in magnified differentiation of cultural groups and their identities in each of the inhabited island groups of Pacific Oceania by A.D. 1000.