AbstractPolymer crystallization is discussed with attention given to primary nucleation, spherulite growth, and bulk crystallization. Primary nucleation is the area of least knowledge, and the authors discuss the kinetics of nuclei appearance and recent observations concerning the effects of foreign materials and surfaces. Spherulitic growth rates are discussed in general and specifically with respect to data at low degrees of supercooling in conjunction with secondary nucleation theory. The Avrami Theory and its limitations are discussed in the interpretation of bulk crystallization data. The authors propose that n = 4 in all cases and that the Avrami Theory be used for calculating the primary nucleation rate, kn, not for determining n itself.