alpha-Methylstyrene (alpha-MSt) and methyl methacrylate were copolymerized at 60 degrees C in toluene by radical polymerization induced by azobisisobutyronitrile. The kinetics were followed by gravimetry and correlated with the molecular weights, microstructure, and glass transition temperature. A model was developed taking into account the equilibrium of the alpha-MSt homopolymerization that could not be neglected at 60 degrees C and higher temperatures. The model is in good agreement with all the experimental data.