The effects of shear rate, residence time, and feed stoichiometry on sequence and chain lengths and polydispersity of product polymer in step growth copolymerization in a microsegregated stirred tank reactor with unpremixed feed streams were investigated. One feed stream contained monomers AA and AX, bifunctional and monofunctional monomers with the reactive group A. The other stream contained monomers BE and DD, short and long types of the bifunctional monomer with the end group B. Mass transport in the reactor was described in terms of diffusion between mobile striations that are stretched by the mean shear rate for time periods that vary according to an exponential RTD. Model results suggest that substantial changes in chain and sequence lengths can be effected when the shear rate is increased at fixed residence time and fixed feed ends-ratio (A to B), particularly when the latter is less than unity. However, the results suggest that when conversion is kept constant by varying the mean shear rate and the mean residence time simultaneously, the influence of shear rate on chain and sequence lengths is minimal. On the other hand, when the feed ends-ratio is varied at constant shear rate and residence time, sequence lengths can vary by appreciable amounts (20-40%). Polydispersity is influenced little by any of the variables that have been studied.