We present an updated classiﬁcation for the entire Crustacea Decapoda, listing all known families and genera organized by higher taxonomic groups and including estimates of the number of species in every genus. All taxonomic names are also linked to the veriﬁed literature in which they were described, the ﬁrst compilation of its kind for the Decapoda. To arrive at this compilation, we began with the classiﬁcation scheme provided by Martin & Davis (2001) for extant families, updated the higher classiﬁcation and included the fossil taxa. The resultant framework was then populated with the currently valid genera and an estimate of species numbers within each genus. Our resulting classiﬁcation, spanning both extant (living) and fossil taxa, is the ﬁrst comprehensive estimate of taxonomic diversity within the entire Decapoda. The classiﬁcation consists of 233 families of decapods containing 2,725 genera and an estimated 17,635 species (including both extant and fossil species). Of the families in our classiﬁcation, 53 are exclusively fossil, 109 contain both fossil and extant species, and 71 are extant only. The current estimate for extant species is 14,756, whereas 2,979 species are known exclusively as fossils.