An attempt to develop a predictive and manageable mathematical model for particle growth in emulsion homopolymerization was carried out by fitting the time evolution of the conversion in the chemically initiated seeded emulsion polymerization of styrene carried out under a wide range of experimental conditions with models of different complexity. Model discrimination based on the best fitting of the experimental data was carried out. No advantage was gained by increasing the complexity of the mathematical model. The dependence of the radical entry and exit rate parameters on the particle size was used to elucidate between the different mechanisms proposed for these processes.