A taxonomic revision of the genus Leiodes Latreille, commonly called round fungus beetles, of North and Central America is presented including a historical review, information on natural history, collecting techniques, diagnostic characters, and a brief discussion of zoogeography. Of the 72 species, in 26 species groups, recognized and illustrated in this volume, 46 are new. Twenty-six are from north of Mexico, 18 from Mexico, one from Mexico and Belize, and one from Panama and Costa Rica.