Abstract. A key and descriptions are given for the four families here recognized for the superfamily Membracoidea Rafinesque, 1815: Cicadellidae Latreille, 1825 (sensu Oman et al., 1990), Melizoderidae, fam.n., Aetalionidae Spinola, 1850 redefined here), and Membracidae Rafinesque, 1815 (redefined here). The following placements are corroborated: Cicadelloidea Latreille, 1825, is a junior synonym of Membracoidea Rafinesque, 1815; Biturritiidae Metcalf, 1951, is a junior synonym of Aetalionidae Spinola, 1850; Nicomiidae Haupt, 1929, is a junior synonym of Membracidae Rafinesque, 1815. The new family Melizoderidae includes two genera: Melizoderes Spinola and Llanquihuea Linnavuori & DeLong. Within Aetalionidae, the subfamily Biturritiinae is redefined to include only five genera. Within the family Membracidae, the subfamily Endoiastinae, subfam.n., is described; the subfamilies Centronodinae Deitz, 1975, status n. (with tribe Centronodini Deitz, 1975, including the genus ParacentronodusSakakibara, 1971, new Placement), and Centrodontinae Deitz, 1975, status n. (with tribe Centrodontini Deitz, 1975), are recognized for the first time; and the following groups are redefined: subfamilies Stegaspidinae Haupt, 1929, Nicomiinae Haupt, 1929, and Membracinae Rafinesque, 1815; and tribe Stegaspidini Haupt, 1929 (Stegaspidinae). The new subfamily Endoiastinae includes three genera: Endoiastus Fowler, Scytodepsa Stål, and Stictodepsa Stål. Endoiastus productus Osborn, 1922, is placed as a junior synonym of Stictodepsa neotropicalis Kirkaldy, 1909, syn.n. Lectotypes are designated and illustrated for Tettigonia muscaria Fabricius, 1803 (now Lophyraspis muscaria) and Cicada fuscata Fabricius, 1803 (now Stictodepsa neotropicalis Kirkaldy, 1909).