Crystalline morphologies of poly(epsilon-caprolactone) (PCL) and polycarbonate (PC) blends were probed with small-angle X-ray scattering (SAXS) and small-angle light scattering (SALS). Quantitative SAXS analysis suggested that random mixing of PCL and PC lamellae occurred in the semicrystalline/semicrystalline state. Two distinct regions of incorporation were identified in the semicrystalline/amorphous state. It was found that PCL was rejected from the PC interlamellar region in the PCL-rich blends. In contrast, PCL was incorporated into the amorphous phase between the crystalline lamellae in the PC-rich blends. This transition from interlamellar exclusion to interlamellar inclusion may be related to the glass transition temperatures or the mobility of the blends. It is proposed that the mode of incorporation or exclusion is governed by the competition between entropy and diffusion. Additionally, SALS coupled with optical microscopy indicated that PC is an effective nucleating agent for PCL crystallization as manifested by the reduction of PCL spherulitic size with the addition of PC.