A number of authors (e. g. Birula, 1917a, 1917b; Mello-Leitão, 1945; Stockwell, 1989) addressed above-level systematics of extant scorpions, and accepted the grouping of scorpion families in several superfamilies. At the same time, Kjellesvig-Waering (1986) classified all extant scorpions under the same superfamily, Scorpionoidea. Sissom (1990) and Fet et al. (2000) did not list any superfamilies, considering the systematic situation above family (and often at the family level as well) unresolved. Most recently, Lourenço (2000a) listed six superfamilies, largely following the unpublished but important study of Stockwell (1989). The goal of this paper is to address scorpion systematics and phylogeny above genus level. We conducted a comprehensive, cladistic morphological analysis of 90 extant genera (over 150 species) of scorpions belonging to all recognized families. We especially concentrated on relationships among so-called “chactoid” scorpions, where subfamilies, tribes, and subtribes were revised and/or established. The family Chactidae was given a special attention due to the number of phylogenetic and taxonomic issues that were revised. In addition, we addressed the status of a recently discovered, unique relict family Pseudochactidae, and the systematic relationships within Iuridae. As a result of intensive study, we propose a number of sweeping changes in current scorpion taxonomy; the results of analyses leading to these changes are discussed in detail. The category of parvorder, subordinate to infraorder, is introduced for the first time in arachnid systematics. Four extant parvorders are recognized within the scorpion infraorder Orthosterni: Buthida, Chaerilida, Pseudochactida, and Iurida. Six extant superfamilies are recognized: Buthoidea, Chactoidea (=Vaejovoidea, syn. n), Chaeriloidea, Iuroidea (new), Pseudochactoidea (new), and Scorpionoidea (=Bothriuroidea, syn. n). Parvorders Buthida, Chaerilida and Pseudochactida are monotypic, each including a single superfamily; parvorder Iurida includes three superfamilies (Chactoidea, Iuroidea, and Scorpionoidea). We recognize 14 extant scorpion families: Bothriuridae, Buthidae, Caraboctonidae, Chactidae, Chaerilidae, Euscorpiidae, Iuridae, Liochelidae, Microcharmidae, Pseudochactidae, Scorpionidae, Superstitioniidae, Urodacidae, and Vaejovidae. Superfamilies Chaeriloidea and Pseudochactoidea are monotypic; superfamily Buthoidea includes two families (Buthidae and Microcharmidae). Superfamily Iuroidea includes two families (Caraboctonidae and Iuridae); subfamily Caraboctoninae (formerly in Iuridae) is elevated to the family rank. Superfamily Chactoidea includes four families: Chactidae, Euscorpiidae, Superstitioniidae (=Troglotayosicidae, syn. n), and Vaejovidae. Within Chactidae, three subfamilies are established: Chactinae, Brotheinae, and Uroctoninae. Within Chactinae, two tribes are established: Chactini and Nullibrotheini, new tribe (monotypic). Within new subfamily Brotheinae, two tribes are established: Brotheini and Belisariini (monotypic). Within Brotheini, two subtribes are established: Brotheina and Neochactina, new subtribe; the latter is based on a new genus, Neochactas, gen. n. Within Brotheina, genera Cayooca, Guyanochactas, and Taurepania are synonymized with Broteochactas. Subfamily Uroctoninae is restored from synonymy under Vaejovidae and transferred to Chactidae; it includes genera Uroctonus and Anuroctonus (the latter transferred from the erstwhile Iuridae). Family Troglotayosicidae is abolished, and its two genera are transferred to other families: Troglotayosicus, to Superstitioniidae; and Belisarius, to Chactidae. Subfamily Belisariinae is downgraded to the tribe rank and transferred to Chactidae (subfamily Brotheinae). Superfamily Scorpionoidea includes four families: Bothriuridae, Liochelidae (=Hemiscorpiidae, syn. n.), Scorpionidae (=Diplocentridae, syn. n.), and Urodacidae (=Heteroscorpionidae, syn. n). Family Diplocentridae is downgraded to the subfamily rank in Scorpionidae. Subfamily Nebinae is downgraded to the tribe rank in Diplocentrinae. Family Hemiscorpiidae is downgraded to the subfamily rank in Liochelidae. Family Heteroscorpionidae is downgraded to the subfamily rank in Urodacidae. We provide detailed classification, taxonomic history, and diagnoses of all recognized scorpion taxa above genus level. The phylogeny and biogeographic implications are discussed. As an addition, we present, among other materials, results of the first pilot high-level scorpion DNA phylogeny, including representatives of seven families spanning all four parvorders. Both morphological analysis and DNA sequence analysis support the primitive nature of parvorders Pseudochactida, Buthida, and Chaerilida, as opposed to the derived position of parvorder Iurida. Especially remarkable is the parvorder Pseudochactida, which exhibits many primitive features. Within Iurida, the superfamily Iuroidea is firmly established as a basal group, and Scorpionoidea, as the most derived group. Phylogeny within Chactoidea shows ancient nature of many clades, as our analysis reveals hitherto unexpected relationships between a number of genera and tribes.