Activators Generated by Electron Transfer (AGET) and Activators Regenerated by Electron Transfer (ARGET) Atom Transfer Radical Polymerization (ATRP) are emerging topics within the polymerization field. These techniques allow for better control over polymer structure and polymer size distributions than conventional polymerizations. However, investigations into these processes are lacking, especially from a modelling point of view. Therefore, a kinetic model of the ARGET ATRP of butyl methacrylate (BMA) in a solution medium and Hybrid Monte Carlo model of the AGET ATRP of butyl acrylate (BA) in a dispersed system were developed and compared with data. In addition, an experimental investigation of the AGET ATRP of BA was carried out to study the kinetic aspects of this polymerization. The results of these studies demonstrate that both models have relatively strong predictive powers, and that different kinetic regimes appear to be available within the dispersed system studied experientially.