Molecular composites, in which a small concentration of ionically modified poly(p-phenylene terephthalamide) (PPTA) is dispersed in a poly(ethylene oxide) matrix, have been prepared. With the content of PPTA anion increasing to about 5 wt %, the glass-transition temperature rises and the melting temperature decreases. From the equilibrium-melting-temperature depression data that were obtained from Hoffman-Weeks plots, the Flory-Huggins interaction parameter was determined to be negative (-1.10). These indications of enhanced miscibility between the components are attributed to intermolecular ion-dipole interactions. The presence of rigid PPTA-anion reinforcement alters the morphology; for example, the spherulite size is reduced, and the degree of crystallinity is lowered. Possible models of how the reinforcement is incorporated into the composite are presented.