Rapid Ecological Assessment (REA) surveys at 465 sites on 11 reefs in the Northwestern Hawaiian Islands (NWHI) inventoried coral species, their relative abundances, and their distributions during 2000 around the 10 islands were in depths of~20 m, and three surveys on the submerged Raita Bank were in depths of 30-35 m. Data from 401 REA sites met criteria for quantitative analysis. Results include 11 first records for stony coral species in the Hawaiian Archipelago and 29 range extensions to the NWHI. Several species may be new to science. There are now 57 stony coral species known in the shallow subtropical waters of the NWHI, similar to the 59 shallow and deep-water species known in the better-studied and more tropical main Hawaiian Islands. Coral endemism is high in the NWHI: 17 endemic species (30%) account for 37-53% of the abundance of stony corals on each reef of the NWHI. Three genera (Montipora, Porites, Pocillopora) contain 15 of the 17 endemic species and most of the endemic abundance. Seven Acropora species are now known from the central NWHI despite their near absence from the main Hawaiian Islands. Coral abundance and diversity are highest at the large, open atolls of the central NWHI (French Frigate, Maro, Lisianski) and decline gradually through the remaining atolls to the northwest (Pearl and Hermes, Midway, and Kure). Stony corals are also less abundant and less diverse off the exposed basalt islands to the southeast (Nihoa, Necker, La Perouse, Gardner), where soft corals (Sinularia, Palythoa) are more abundant. Exposure to severe wave action appears to limit coral development off these small islands and surrounding deep platforms. Temperature extremes and natural accumulation of lagoon sediments may contribute to decline of coral species and abundance at the northwestern end of the chain. Some NWHI land areas were severely degraded by logging, alien species, mining, agriculture, and military use since the late nineteenth century, but the islands today support millions of seabirds and migratory shorebirds; endangered land and water birds; terrestrial plants; and nesting and feeding grounds of threatened sea turtles and endangered Hawaiian monk seals. By contrast, the adjacent reef and shore areas have been relatively unaffected by human activity, although parts of some reefs have been exposed to marine debris (especially trawl and drift nets), invasive species (especially at harbors and on marine debris), chemical contaminants, fisheries, bioprospecting, coral bleaching, and ship groundings.Most knowledge of Hawaiian corals is restricted to reefs around the eight inhabited Coral Species and Distributions in the NW Hawaiian Islands . Maragos et al. 213 main Hawaiian Islands (from Ni'ihau to Hawai'i) and is still based largely on the studies of Dana (1846) and Vaughan (1907). Major compilations of corals from the main Hawaiian Islands since then include Edmondson (1933Edmondson ( , 1946, Maragos (1977Maragos ( , 1995, and Veron (2000), who included descriptions and photographs of e...