The aim of the present investigation is the development of a unifying framework for modeling free-radical suspension and bulk vinyl chloride polymerizations. A fairly comprehensive but realistic model is described that has the ability to predict the rate of polymerization as well as the molecular properties of polymer as a function of the process conditions. It is shown that no significant differences exist between the predictions of the present model and those obtained by various well-known two-phase PVC models published before. in addition to the prediction of fractional monomer conversion and rate of polymerization, the new model predicts the anomalous structures observed in commercial PVC, namely, the number of short- and long-chain branches as well as the number of unsaturated terminal double bonds per polymer molecule. Simulation results show that the present model provides realistic predictions of the important molecular properties in agreement with experimental observations reported in the literature. Finally, the validity of the quasi-steady-state approximation for growing macroradicals is tested by comparing conversion and molecular weight results obtained with or without its application.