Cucujidae sensu lato is comprised of 97 genera and over 1,000 species worldwide. This group is currently split into four families: Silvanidae, Passandridae, Cucujidae, and Laemophoeidae. The biology of these beetles is mostly poorly known, but the group includes fungivores, ectoparasites, and predators. Some species are important pests of stored grain while others are potentially beneficial biocontrol agents of wood-boring pests. The objectives of this study are to (1) test the monophlyly of Cucujidae s.l.; (2) test the monophyly of, and relationships among, Silvanidae, Passandridae, Cucujidae, and Laemophoeidae; and (3) investigate the evolution of feeding habits. A broad range of exemplars (~50 taxa) was sequenced from throughout Cucujoidea with an emphasis on the families comprising Cucujidae s.l. Sequences were generated from the following genes: 12S rDNA, 16S rDNA, 18S rDNA, 28S rDNA, COI, and COII mtDNA. Trees were reconstructed under multiple optimality criteria to produce a robust phylogenetic hypothesis, and the feeding biology of these beetles was mapped on the tree in order to decipher evolutionary patterns of food utilization.