An alternative approach to model emulsion polymn. is presented that is capable of rigorously solving both particle and radical kinetics for emulsion polymn.: the explicit radical-particle size distribution approach. The method is based on a direct soln. of all population balances and fully covers the strong influence of compartmentalization on rates of reactions between macroradicals and, consequently, on chain length avs. An essential and new feature is the compartmentalization factor (Df), which accounts for compartmentalization in a transparent manner. The generic approach allows for studying the complete emulsion polymn. conversion range, including gel-effect, and the effect of various parameters on both chain length and particle size distribution. Well-known kinetic regimes for emulsion polymn. naturally arise as limiting cases from our model. The dynamic behavior of the model was studied by simulating several realistic seeded emulsion polymn. reactions for styrene. The model dealt with compartmentalization accurately and was able to correctly reproduce the dynamic behavior known to be typical for emulsion polymn.