The distribution, species composition, and zonation of reefs on the island of St. Vincent are described and compared with corresponding characteristics of several other Caribbean and Bahamian reefs. Reef-building organisms are restricted to the leeward coast adjacent to the older volcanic mountains where broad, shallow shelves are present and where the influx of inorganic sediment is at a minimum. Well-developed reef structures are few in number and are somewhat restricted in size. However, those present show distinct zonation and a diverse coral, sponge, and algae assemblage. St. Vincent reefs are generally smaller than the reefs of Barbados, Jamaica, or the Bahamas. The assemblage of organisms is much less diverse, but the over-all morphology is similar in most cases.