The evolution of crystallinity of neat PPS and of the carbon fiber reinforced polymer under different processing conditions is studied. Crystallization from the amorphous state at low temperatures (cold crystallization), crystallization from the melt during cooling, and crystal melting processes are analyzed using calorimetric techniques under both isothermal and nonisothermal conditions. Cold and melt crystallization kinetics are described using an Avrami equation and an Arrhenius expression for the temperature dependence of the kinetic constant. Also, the melting kinetics of the, reinforced and of the unreinforced polymer are studied in this work. The effect of carbon fibers on the crystallization kinetics of PPS is analyzed, and a comparison of the crystallization behavior of PPS and other semicrystalline thermoplastic matrices, such as poly(etheretherketone) (PEEK), is presented.