The equilibrium thermodynamic properties and crystallization behavior of poly(p-phenylene succinate) (PPSc) were examined using differential scanning calorimetry (DSC) and a wide-angle X-ray diffractometer. When PPSc quenched into liquid nitrogen, the PPSc still showed 60 J/g of the heat of fusion, indicating that PPSc crystallizes too fast to be quenched to a glassy state. The equilibrium heat of fusion (Delta H degrees) of PPSc and its equilibrium entropy of fusion (Delta S degrees) were estimated to be 28 and 48 J/mol K, respectively. The effect of the molecular weight and undercooling on PPSc crystallization was analyzed by the Avrami expression. The crystallization rate of PPSc was highest at about 276 degrees C, regardless of molecular weight when the sample was isothermally crystallized. This temperature was higher than that of poly(ethylene terephthalate) (PET) by 100 degrees C. The crystallization rate was highest when the number average molecular weight of PPSc was about 20,000 g/mol.