Melt blending of Bisphenol A polycarbonate (PC) and poly(trimethylene terephthalate) (PTT) was carried out over the entire composition range. The mixing time was varied up to 90 min. The resulting samples were analyzed by FT-IR, DSC, XRD, DMTA, 1 H NMR, and SEM. The process of transesterification between the two polymers and their resulting compatibilization were observed. The behaviors of the PTT-rich and PC-rich blends were different and an equilibrium was found to exist. Peculiar behavior, which was different from that of the PTT-rich and PC-rich blends, was exhibited by the 50/50 (PTT/PC) blend.