Renewable alternatives to petroleum-based thermosetting polymers have drawn significant attention due to potential positive economic and ecological impact. New materials should mimic the rigid, phenylic structure of incumbent high-performance thermoset monomers. Furans derived from cellulose and hemicellulose are promising candidates for phenyl replacement. The synthesis of furan-based diepoxies is challenging, and direct property comparisons of thermosets prepared using furanyl and phenyl-based epoxy monomer analogues are required. In this work, analogous furanyl-based and phenyl-based diepoxy monomers were synthesized, and thermosets were prepared using amine curing agents. A structure property study showed that furan-based polymers possess improved T-g (Delta = 8-16 degrees C) and improved glassy modulus (Delta = 0.1 to 0.6 GPa) relative to their phenylic analogues. The furan ring has thus been demonstrated to be a viable building block for renewable high-performance epoxies, with potential for application in other thermosetting polymers.