Dr. Frost is interested in the evolutionary origin and diversification of amphibians and reptiles, as well as the underlying epistemological issues of knowledge claims in evolutionary biology. He has published widely on these topics, including the notion of species, how to combine different lines of evidence in phylogenetic analysis, and the practical elucidation of the phylogeny of various amphibia and reptile groups. These efforts have resulted in revised classifications of iguanian lizards (ca. 1000 species), as well as a general classification and revision of all amphibians (ca. 5800 species). The latter was based on the largest phylogenetic tree ever calculated for a vertebrate group and which for the first time provided a comprehensive understanding of the major monophyletic groups of amphibians. At the other extreme, Dr. Frost maintains a very large online taxonomic catalogue of the world's living amphibians, found at http://research.amnh.org/herpetology/amphibia/index.html, which provides the nomenclatural history, available English names, geographic distribution, and a digest of the relevant literature regarding the taxon. He feels strongly that meticulously prepared catalogues help knit the world's scientific community together by providing workers in the developing world with access to current literature and up-to-date summaries of our knowledge of the biodiversity of living amphibians.