Phylogenetic relationships within the diverse beetle superfamily Cucujoidea are poorly known. Of the few superfamilial cucujoid groups that have been proposed to be monophyletic, the largest is the Cerylonid Series, comprising eight families and representing most of the known cucujoid species diversity. The monophyly of the Cerylonid Series, however, has never been formally tested and the higher-level relationships among and within the constituent families remain equivocal. DNA sequence data (18S and 28S rDNA) were obtained for a broad taxonomic sampling within the Cerylonid Series and other cucujoid taxa. Phylogenetic analyses of these data were performed to test the monophyly of the Cerylonid Series, place the Cerylonid Series among the remaining cucujoid families, investigate the relationships among the Cerylonid Series families, and test the monophyly of the constituent families. These data support the monophyly of the families Bothrideridae, Discolomatidae, Corylophidae, and Coccinellidae. Corylophidae is nested within Latridiidae rendering the latter paraphyletic, while Endomychidae is grossly polyphyletic. Other taxonomic and biological implications are discussed in light of this phylogeny.