Cumberland Island National Seashore, Camden County, Georgia, is administered by the National Park Service, United States Department of the Interior, and comprises 14,740 ha (36,415 acres) that include property and historic residences once owned by the Thomas Carnegie family. A floristic survey of the 7,880 ha (19,472 acres) owned by the National Park Service was conducted to provide Park Service personnel with a vouchered plant species checklist, supplemented with salient information such as relative abundance, locality data, and general community type. Six intensive collecting trips conducted in 2004–2006 yielded 498 species of plants, including 233 species not previously vouchered for the Island. The four largest families were Poaceae, Cyperaceae, Asteraceae, and Fabaceae. Identifications of specimens in the Cumberland Island National Museum Herbarium were also verified and incorporated into the annotated list. Maps, descriptions, and photographs of the various plant communities are provided.