The application of the well-known soap titration method, originally developed to determine the size of latex particles, to the characterization of the average droplet size of octadecyl methacrylate (ODMA) and styrene (St) miniemulsions was investigated. Control experiments were first performed using individual monodisperse polystyrene latexes of known size and then mixtures of these to create broad (multimodal) distributions. The surfactant (soap) titration method was applied to determine the effect of the particle size distribution on the accuracy of the method. The average particle sizes (D-vs, volume-surface average diameter) obtained were in good agreement with both the experimental (capillary hydrodynamic fractionation, CHDF) and calculated particle sizes. Next, the droplet size of ODMA miniemulsions (with and without hexadecane as costabilizer) was characterized by both soap titration and CHDF. The two measurements were found to be in good agreement, proving the viability of the technique in sizing emulsion droplets. Various styrene miniemulsions were then characterized by soap titration. By increasing the SLS concentration used in the preparation of the miniemulsions, the droplet size decreased as expected. It was also found that the presence of TiO2 particles dispersed within the monomer phase prior to forming the miniemulsion droplets leads to an increase in the droplet size. In addition, an increase in the TiO2 content resulted in an increase in the average droplet size, indicating a greater number of TiO2 particles within each droplet. These measurements are important for assessing the extent of droplet nucleation that; might be expected in subsequent polymerizations. Low free-surfactant concentrations (less than critical micelle concentration) and small droplets (large in number) favor nucleation in droplets, as opposed to homogeneous or micellar nucleation.