In this article, we report the combined effects of poly(ethylene glycol) (PEG) and/or graphene oxides (GOs) on the crystallization behavior of poly(l-lactide) (PLLA) under different crystallization conditions, such as nonisothermal crystallization, isothermal crystallization, and annealing-induced cold crystallization. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction, and polarized optical microscopy were used to study the crystallization kinetics and crystallinity to illustrate the effects of PEG and/or GOs on the crystallization behavior of PLLA. The results show that PEG functioned as a plasticizer and improved the chain mobility of /PLLA during crystallization and the GOs acted as efficient nucleation agents and accelerated the crystallization rate. Finally, both PEG and GOs improved the crystallization ability of PLLA. Importantly, the simultaneous addition of PEG and GOs led to a synergistic effect on the crystallization behavior of PLLA under all conditions. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3498-3508, 2013