The kinetics of the high solids content emulsion terpolymerization of vinyl acetate, methyl methacrylate, and butyl acrylate were investigated. The effect of feed flow rate, total amount of emulsifier, distribution of emulsifier between the initial charge and the feed, concentration of initiator, and solids content on the time evolution of the conversion, terpolymer composition, and total number of polymer particles were investigated. The experimental results were analyzed by means of a mathematical model that incorporated the main features of the system.