The miscibility, morphology, and crystallization behavior of the blend of poly(ethylene oxide) (PEO) and poly(butylene succinate) (PBS) have been investigated using differential scanning calorimetry, high-resolution solid-state C-13 NMR spectroscopy, and wide- and small-angle X-ray diffraction. PEO and PBS are found to be miscible in the amorphous phase, and fractional crystallization of PEO component is observed in the blends with low PEO content. Also, it is revealed that the PEO component in the blend with less than 20 wt % PEO content is completely included in the region between PBS lamellae. On the basis of these results, the crystallization behavior of the PEO component has been analyzed and the origin of fractional crystallization has been explored. The blend system of PBS and PEO investigated here is the first instance of confined and fractional crystallization occurring in a miscible blend.