The room-temperature, tensile mechanical properties and fracture topographies of a range of polyamide-cured bisphenol-A-diglycidyl ether epoxies with differing physical characteristics are reported. Epoxies of different physical structure were prepared by varying the initial physical state of the epoxy monomer (crystalline versus noncrystalline), the cure conditions, and the initial epoxy:polyamide curing agent ratio. Epoxy monomer crystals (mp 41.5°C) present in the unreacted epoxy remain embedded in the room-temperature partially cured glass. Exposure of this epoxy to 48°C produces liquidus islands of unreacted epoxy monomer which locally enhance crazing. At higher temperatures, the unreacted epoxy monomer escapes, leaving microvoids which collapse as the glass softens. Unreacted epoxy monomer also recrystallizes between microgel regions of high crosslink density at room temperature. The resultant liquid produced by melting these crystals causes homogeneous plasticization. Volatilization of the unreacted monomer produces a network structure of poor integrity between the original microgel regions which causes a brittle mechanical response. Fracture topography studies indicate that epoxies generally fail by void growth and coalescence through a simultaneously growing craze. It is suggested that flow occurs during failure by islands of high cross link density moving past one another.