In our study we examined 4151 preserved frogs, 93 skeletal preparations, 88 lots of tadpoles and young, and six lots of eggs. We have collected specimens in the field of all of the species. Observations on behavior and life history were begun by the senior author in Mexico in 1956 and completed by us in Central America in 1964 and 1965. Osteological data were obtained from dried skeletons and cleaned and stained specimens of all species, plus serial sections of the skull of _Smilisca baudini_. Developmental stages to which tadpoles are assigned are in accordance with the table of development published by Gosner (1960). Breeding calls were recorded in the field on tape using Magnemite and Uher portable tape recorders. Audiospectrographs were made by means of a Vibralyzer (Kay Electric Company). External morphological features were measured in the manner described by Duellman (1956). In the accounts of the species we have attempted to give a complete synonymy. At the end of each species account the localities from which specimens were examined are listed alphabetically within each state, province, or department, which in turn are listed alphabetically within each country. The countries are arranged from north to south. Abbreviations for museum specimens are listed below: AMNH--American Museum of Natural History BMNH--British Museum (Natural History) BYU--Brigham Young University CNHM--Chicago Natural History Museum KU--University of Kansas Museum of Natural History MCZ--Museum of Comparative Zoology MNHN--Museu National d'Histoire Naturelle, Paris UF--University of Florida Collections UIMNH--University of Illinois Museum of Natural History UMMZ--University of Michigan Museum of Zoology USC--University of Southern California USNM--United States National Museum TNHC--Texas Natural History Collection, University of Texas ZMB--Zoologisches Museum Berlin =Genus Smilisca= Cope, 1865 _Smilisca_ Cope, Proc. Acad. Nat. Sci. Philadelphia, 17:194, Oct., 1865 [Type species _Smilisca daulinia_ Cope, 1865 = _Hyla baudini_ Dumeril and Bibron, 1841]. Smith and Taylor, Bull. U. S. Natl. Mus., 194:75, June 17, 1948. Starrett, Copeia, 4:300, December 30, 1960. Goin, Ann. Carnegie Museum, 36:15, July 14, 1961.