During the 2003 breeding season 367 historic, potential, and current nesting sites of larids (Fam. Laridae) along the coast of western Mexico were surveyed. In 2004 and 2005, three areas: Guerrero Negro, in Baja California Sur; Marismas Nacionales, in Nayarit-Sinaloa; and Laguna Cuyutlán, in Colima were surveyed more intensively. In 2003-2005, there were nine nesting sites and probably between 200 and 300 breeding pairs of Caspian Tern (Sterna caspia); eleven confirmed nesting sites and at least 13,000 breeding pairs of Royal Tern (S. maxima); two nesting sites, one of which included almost the entire population, and 90,000 breeding pairs of Elegant Tern (S. elegans); four nesting sites and about 20 breeding pairs of Forster’s Tern (S. forsteri); and 13 nesting sites and about 1,000 breeding pairs of Black Skimmer (Rynchops niger). Breeding of Caspian and Elegant Terns on the Pacific coast of Mexico is confined to the northern areas, whereas that of Royal Terns and Black Skimmers occurs at selected sites along most of the coast. Forster’s Terns nest in two widely separated areas, one in the northern section of the coast, and one in the southern section.