The effects of agitation in a ca. 24% solids semibatch emulsion copolymerization of n-butyl methacrylate and N-methylol acrylamide in a 2 dm(3) reactor are reported. A Rushton turbine with 8 cm tip-to-tip diameter was used as the agitator. The agitation speeds during the seed and feed stages of the semibatch process were varied at two levels. The final latexes obtained from the four experiments were characterized for the size of the polymer particles, viscosity, amount of water-soluble polymer, and the amount of coagulum at the end of the reaction. A higher agitation speed nucleated a greater number of polymer particles during the in situ seed formation step (seed stage). In the absence of any secondary nucleation during the monomer-feeding stage, the final latexes had a higher number of particles when the agitation speed during the seed stage was higher. The amount of coagulum increased with an increase in the agitation power-input. The amount of water-soluble polymer was influenced mainly by the agitation during the seed stage of the process, through the effect of the latter on the number of polymer particles. However, the pooling of the BMA monomer during the feed stage, because of poor mixing and shear in the reactor, resulted in an increased water-soluble polymer formation. Latexes prepared using a higher agitation speed during the seed stage had a higher viscosity.