Blends of phenolphthalein poly(ether ether sulfone) (PES-C) with a thermotropic liquid crystalline copolyester (LCP) were prepared. Miscibility, morphology, thermal behavior, and mechanical properties of the PES-C/LCP blends with various compositions were studied by using differential scanning calorimetry (DSC), wide-angle x-ray diffraction (WAXD), dynamic mechanical analysis (DMA), tensile tests, and scanning electron microscopy (SEM). Both DSC and DMA studies showed that the blends have two glass transition temperatures (Tg) corresponding to those of the PES-C-and LCP-rich phases, respectively. PES-C and LCP are partially miscible, theTg's varying with composition. Young's modulus increases slightly with increasing LCP content owing to the high modulus of LCP, whereas the tensile strength greatly decreases with increase of LCP content. The interfaces between PES-C and LCP are weakly bonded, with rather poor interaction. SEM observations revealed that the blends have a two-phase structure and that the adhesion between the phases is poor.