The temperature-dependent micellization of Pluronic F127 (EO99-PO65-EO99, EO and PO being ethylene oxide and propylene oxide, respectively) was investigated experimentally and theoretically. While experiments involved the determination of the temperature dependence of the critical micellization concentration (cmc) and the fraction of polymer molecules in micellar form, the theoretical results were obtained through a self-consistent lattice theory for multicomponent mixtures of copolymers with internal states in heterogeneous systems. Comparison between theoretical and experimental findings shows qualitative agreement regarding the decrease in the cmc and the increase in the average aggregation number, the micellar size, and the fraction of polymer molecules in micellar form, all with increasing temperature. Furthermore, details about the temperature-dependent micellization, obtained from the model calculations, are discussed,