This work catalogues the changes to the classification of treehoppers (Membracoidea, families Aetalionidae [including Biturritiinae], Melizoderidae, and Membracidae [including Nicomiinae]) world-wide from 1956 through 1994 and provides a current list of all valid taxa and all synonyms. All subsequent references discovered by April 1997 were also incorporated. The only new taxonomic change made herein is the fixation of the correct original spelling of Notogonioides McKamey, which had been misspelled once in the original publication. World Membracoidea (exclusive of leafhoppers) now consists of 15 subfamilies, 53 tribes, 402 genera, and 3166 species. Fossil taxa (2 subfamilies and 10 genera) and 2 extant species erroneously described or listed as treehoppers and later referred elsewhere (to Cicadellidae, Coleorrhyncha, Heteroptera, Orthoptera, or unplaced Cicadomorpha) also are catalogued – fossils of true treehoppers are known from Dominican amber, but have not been described. Literature citations through 1987 correspond to references given in previous bibliographies of the Membracoidea; a bibliography is provided for subsequent taxonomic publications.