In the presence of polycarbonate (PC), the polymerization of diglycidyl ether of bisphenol A (DGEBA) and bisphenol A in the melt was initiated to prepare blends of poly(hydroxyether of bisphenol A) (phenoxy) and PC. The polymerization reaction started from the initially homogeneous ternary mixture consisting of DGEBA, bisphenol A, and PC; phenoxy/PC blends with PC content up to 20 wt % were obtained. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to characterize the miscibility of the as-polymerized blends. All the blends displayed separate glass transition temperatures (T-g's), that is, the blends were phase separated. The formation of a two-phase structure is considered to result from phase separation induced by polymerization. This result is consistent with the immiscibility established through solution- and melt-blending approaches. The insolubility of the as-polymerized blends showed that crosslinking between the components occurred. Both Fourier-transform infrared (FTIR) and solid C-13-nuclear magnetic resonance (C-13-NMR) spectroscopic studies demonstrated a transreaction between the components and in situ polymerization of DGEBA and bisphenol A in the presence of PC, which yielded a phase-separated, transreacted material. The results of this work provide a contrast to those of the transreacted phenoxy/PC blends based on conventional blending methods; however, the transreaction in the present case occurred at a much lower temperature (180 degrees C), at which polymerization blending was carried out.