Polypropylene (PP)/wasted poly(ethylene terephthalate) (PET) fabric composites and these composites modified by maleic anhydride grafted polypropylene (PP-g-MA) and reactive monomers were prepared with a twin-screw extruder. The crystallization morphology, nonisothermal crystallization and melting behavior, crystallization kinetics, and isothermal crystallization kinetics were investigated with differential scanning calorimetry. The results indicated that the wasted fabric (WF) had a heterogeneous nucleation effect on PP in the composites, and this increased the crystallization temperature and induced PP to form transcrystallinity. PP-g-MA further increased the crystallization temperature; however, the reactive monomers weakened the heterogeneous nucleation effect of WF. Also, the premelting temperature affected the crystallization and melting behavior of the composites significantly. The Avrami equation and the Mo method provided a fairly satisfactory description of the crystallization kinetics. The crystallization activation energy, nucleation constant, and folding surface free energy of PP were markedly reduced in the PP/waste PET fabric composites and the compatibilized composites. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121:1972-1981, 2011