Only a few scattered references to the lepidopterous fauna of Santa Catalina Island are found in scientific literature. During the past forty years many entomologists have visited the island and collected for brief periods, usually in the neighborhood of Avalon, but until the material for this paper was assembled no extensive collections of island butterflies and moths were made. During the years 1927 to 1934 insects were netted at all seasons on all parts of the island, and during 1932 and 1933 light traps for moths were operated at Avalon and Middle Ranch. Excluding the micro-lepidoptera, which have not yet been worked up. 167 species of lepidoptera were taken.