St. Vincent Island is one of the barrier islands in the Florida panhandle between Apalachicola Bay and the Gulf of Mexico. The St. Vincent National Wildlife Refuge encompasses all 5000 hectares of the island. Archaeological fieldwork in the summer of 2009 included a survey of the entire island and a test unit at one of the island's richest sites. In spring of 2010 a second test unit was excavated at another archaeologically rich site. A total of 16 known sites were investigated and two newly discovered sites recorded. This research combines all these data with information obtained from existing artifact collections and archives, as well as results of a widespread geological survey of the island, in order to characterize the prehistoric archaeological record on the island, which stretches back at least 4000 years or more, to the time of the island's first formation. Subsistence, settlement patterns, site use, and change through time in the human adaptation on St. Vincent are described in relation to the preexisting cultural chronology of the region, especially that of other barrier islands. Settlement from all time periods is concentrated on the north and east shorelines, with not much human use of the island interior until recent historic time. Geological indication of sea level fluctuations on the islands oldest shoreline section, on the northeast tip, is combined with archaeological evidence to suggest responses to rising sea levels.