An effective model for the bulk, solution and suspension copolymerization of styrene/divinylbenzene has been developed. Experimental data from different sources and model predictions are in very good agreement in most cases for pre and post-gelation periods. The effects of solvent, chain transfer agent, inhibitor, type and concentration of crosslinker (m-DVB, p-DVB or a mixture of both), type and concentration of initiator, and temperature are accounted for by the present model.