A mathematical model of the basic polymerization kinetic scheme, that involves only initiation, propagation, and termination reactions, has been developed. It was assumed that the propagation and termination rate constants are independent of the chain length. It has been shown that the model predicts the effect of autoacceleration on the formation of the insoluble polymer component. In order to demonstrate the applicability of the mathematical model for description of dispersion radical polymerization, the evolution of the size distribution of growing polystyrene particles has been measured with the Flying Light-Scattering Indicatrix method.