This study investigates the coupled effects of mild shear flow and temperature on the crystallization behavior of two thermoplasticpolymers, namely, an isotactic polypropylene and an isotactic poly(1-butene). Rheological experiments are used to measure thecrystallization induction time under isothermal, steady shear flow conditions. The experimental results clearly show the effects of the degreeof undercooling on flow-induced crystallization (FIC). As temperature decreases, the corresponding increase in chain orientation at a givenshear rate leads to an absolutely faster crystallization. At the same time, however, a temperature decrease makes the flow-induced drivingforce to crystallization relatively less influent with respect to the intrinsic kinetics. A FIC model based on the Doi–Edwards microrheologicaltheory is shown to successfully describe the quantitative details of the observed experimental behavior.