A kinetic model has been developed to simulate the shear-induced coagulation process during semibatch seeded emulsion polymerization of acrylic monomers. DLVO theory was used to calculate the potential energy barrier against coagulation of the latex particles. The coagulation rate constant was postulated to be proportional to an exponential function of the relatively mean free path length between two particles. Experimental data available in the literature were used to evaluate the proposed model. Agreement between the model predictions and experimental data was good. The model was then used to study the effects of important reaction parameters (such as the total solids content, seed particle size and concentration, initiator concentration, and surfactant feed profile) on the stability of the emulsion polymer produced in a semibatch reactor.