The effect of self-nucleation on the nonisothermal and isothermal crystallization behaviors of the segmented copolymer poly(ether ester), based on poly(ethylene glycol) as the soft segment and poly(ethylene terephthalate) as the hard segment was investigated by means of differential scanning calorimetry (DSC) and depolarization polarized light (DPL) techniques, respectively. The results demonstrated that selfnucleation could enhance the crystallization rate in both cases. The experimental conditions of the self-nucleation procedure studied by DSCwere discussed in detail. The isothermal crystallization was analyzed by the Avrami equation, and the Avrami parameters were dependent on the melting temperature.