Miniemulsion polymerization is mechanistically distinct from the conventional emulsion polymerization in several aspects; the most important being that the nucleation occurs in the small and stable monomer droplets. This process is being used to produce polymer latexes of unusual characteristics. The initial droplet size distribution and the final particle size distribution in miniemulsion polymerization are broad. This has not been addressed by the present models, which are based on the grosser perspectives of this system and assume monodisperse droplet size and particle size distributions. A population balance model for the miniemulsion polymerization that incorporates the particle size distribution is developed in this work. The model predictions are verified against data taken from the literature.