The estimation of kinetic parameters is a critical part of developing a process model for industrial polymerization processes. In transition-metal-catalyzed gas-phase olefin copolymerization processes, polymer density is a strong function of the amount of higher alpha-olefin comonomers incorporated into the polymer. For the calculation of copolymer composition with a process model, propagation rate constants, which vary from one catalyst system to another, must be known. In this paper, several computational methods applicable to batch, semibatch, and continuous reactors are presented to estimate the propagation rate constants and reactivity ratios in gasphase olefin copolymerization processes.