We examined nest sites of Red-tailed Tropicbirds (Phaethon rubricauda) on Rose Island of the Rose Atoll National Wildlife Refuge, American Samoa, to determine habitat features important for nest-site selection of this species. We quantified habitat characteristics at 27 nest sites and at 27 random sites during September 1991. All nests were located under beach heliotrope (Messerschmidia argentea) shrubs or pisonia (Pisonia grandis) trees. Nest sites were placed farther under the nest shrub, had more stems in the nest space, and greater percent shade cover than random sites. Nest sites averaged 24.9 m from their nearest neighbor, ≥20 m greater than has been reported elsewhere for this colonial species. We suggest that an overpopulation of Polynesian rats (Rattus exelans) may have influenced nest-site selection by Red-tailed Tropicbirds on Rose Island.