Phylogenetic relationships among the basal Cucujoidea were reconstructed by a cladistic analysis of a data matrix consisting of 37 exemplar taxa and 99 adult and larval characters. Eight most parsimonious cladograms provided evidence for the polyphyly of Phloeostichidae, the paraphyly of Cucujoidea (with respect to the placement of Trogossitidae), and the monophyly of Protocucujidae + Sphindidae, Biphyllidae + Erotylidae, Cryptophagidae, Cucujidae + Silvanidae, Propalticidae + Laemophloeidae, and the Nitidulidae groups (Nitidulidae, Smicripidae, and Brachypteridae). The following families are elevated from subfamily to family status: Agapythidae (one genus), Phloeostichidae (four genera; the subfamilies Phloeostichinae and Hymaeinae are supressed), Priasilphidae (three genera), Tasmosalpingidae (one genus), and Myraboliidae (one genus). These families are described in detail and adult and larval keys to all families of Cucujoidea are provided. The genus Bunyastichus, gen. nov. (type species: B. monteithi, sp. nov.) is described in the family Phloeostichidae and the family Priasilphidae is revised with the following new taxa: Chileosilpha, gen. nov. (type species: C. elguetai, sp. nov.), Priasilpha (P. angulata, sp. nov., P. aucklandica, sp. nov., P. bufonia, sp. nov., P. carinata, sp. nov., P. earlyi, sp. nov., and P. embersoni, sp. nov.), Priastichus (P. crowsoni, sp. nov. and P. megathorax, sp. nov.).