Toughenability of cyanate ester networks with reactive hydroxyl-functionalized phenolphthalein-based amorphous poly(arylene ether sulfone) thermoplastics, via conventional thermal curing, without a sacrifice in either the T-g or the moderately high modulus of the unmodified cyanate ester networks was already demonstrated. The present article investigated the rapid processing of unmodified and thermoplastic-modified cyanate ester networks utilizing microwave radiation. Controlled morphologies were generated by variations in both the rates of conversion and the thermoplastic compositions. Improved toughness can be achieved which can be coupled with significantly reduced curing times. The use of nonreactive modifiers resulted in macrophase separation in contrast to the well-defined morphologies of the reactive thermoplastic-modified networks.