A dynamic model is presented that successfully simulates an emulsion polymerization of styrene and butadiene carried out in an industrial train of continuous stirred-tank reactors. It is based on previous publications (Broadhead et al., 1985; Kozub, 1989); but it also includes: a) a set of partial differential equations to calculate the particle size distribution; and b) the effect of specific impurities such as oxygen and vinylacetylene. The model adjustment involved a set of steady-state (SS) experiments, with measurements along the reactor train of conversion, copolymer composition, molecular weights, and particle size. Minimum-time transients between two SS＇s were successfully simulated.