A survey of container-breeding mosquitoes was conducted on urban islands (Big Coppitt Key, Rockland Key, Key West, and Stock Island) and rural islands (Big Pine Key, Cudjoe Key, Little Torch Key, No Name Key, Ramrod Key, Saddlebunch Keys, Sugarloaf Key, and Summerland Key) within the Florida Keys. Five mosquito species were collected: Aedes aegypti, Culex nigripalpus, Cx. quinquefasciatus, Cx. salinarius, and Ochlerotatus taeniorhynchus. Plastic buckets, trash cans, and discarded plastic containers most commonly were found to be mosquito breeding sites. Many containers were used by more than 1 mosquito species. More containers holding water were found in the rural areas than in the urban areas. The percentage of wet containers with mosquitoes did not differ between the rural and urban areas.