Macroscopic phenomena in suspension polymerization reactors are extremely complex, and breakage and coalescence of polymerizing monomer droplets are not well understood, especially for high dispersed-phase volume fractions. Depending on the agitation, concentration and type of surface-active agent the droplet size call exhibit a U shape variation with respect to the impeller speed. This behavior has been confirmed experimentally and theoretically as the balance between breakage and coalescence rates of monomer drops. Both processes are related to the drop surface energy, which is proportional to the interfacial tension and its variation with time. In this study die most comprehensive models describing breakage and coalescence processes in a dispersion system were incorporated into a generalized numerical algorithm to predict the steady-state drop-size distributions in a high holdup (50%) liquid-liquid dispersion system. To assess the effectiveness of the theoretical model in simulating drop-size distributions in high holdup dispersion systems, experiments were carried out with a model system of 50% n-butyl chloride in water in the presence of a surface-active agent, poly(vinyl alcohol), at different concentrations and agitation rates. The theoretical model can predict reasonably well the drop-size distribution for all experimental conditions A systematic theoretical and experimental investigation elucidates the relationships between the changing structure of PVA molecules at the monomer/water interface and their effects on breakage and coalescence frequencies at different agitation times and rates.