This paper is a brief review of the overall crystallization kinetics of synthetic homopolymers. The basic experimental results are presented and compared with theory that is currently available. It is found, surprisingly, that the more sophisticated theories do no better in explaining experimental results than does the free-growth approximation. This is contrary to what is observed for the crystallization of low molecular weight substances. The reason can be attributed to entanglements and other topological defects that are present in the pure melt and are relegated to the non-crystalline regions as crystallization progresses. This results in a more protracted crystallization than is predicted and is yet to be included in theory.