Black Skimmers (Rynchops niger) are widely distributed along the eastern and southern coasts of North America. Along the western coast their distribution is more restricted, ranging from Mexico north to southern California (American Ornithologists’ Union 1983, Collins and Garrett 1996); a few pairs have nested recently in coastal northern California (Yee et al. 1995, Layne et al. 1996). The ecology, reproductive biology, and behavior of Black Skimmer populations along the Atlantic coast and Gulf of Mexico have been the subject of numerous investigations (Erwin 1977, 1979, Loftin 1982, Custer and Mitchell 1987, Quinn 1989, 1990, Burger and Gochfeld 1990) and have been reviewed by Gochfeld and Burger (1994). The potential effects of environmental contaminants on these populations have also been described in several recent publications (Blus et al. 1980, White et al. 1984, King et al. 1986, King 1989, and Burger and Gochfeld 1992). Except by Schew and Collins (1990, 1991), little information has been published on the Pacific coast breeding populations. Black Skimmers nesting at the Salton Sea, a large interior saline basin in extreme southern California, have received only cursory attention since the establishment of breeding in 1972 (McCaskie et al. 1974, Grant and Hogg 1976, Grant 1978). This unique interior population is well established, having persisted for nearly 25 years. In this paper I describe the nesting habitat, population trends, phenology, clutch size, and hatching success of Black Skimmers nesting at the Salton Sea during the 1990s.