A series of miniemulsion systems based on styrene/azobisisobutyronile in the presence of poly(methyl methacrylate-b-2-(dimethylamino)ethyl methacrylate) as a surfactant and hexadecane (HD) as a cosurfactant were developed. For comparison, a series of pseudoconventional emulsions also were carried out with the same procedure used for the aforementioned series but without the cosurfactant (HD). Both the droplet size and shelf life were also measured. Experimental results indicate that it is possible to slow the effect of Ostwald ripening and thereby produce a stable miniemulsion with the block copolymer as the surfactant and HD as the cosurfactant. In addition, the extent to which varying the surfactant concentration and copolymer composition could affect both the polymer particle size during the polymerization and the polymerization rate was examined. Variation in the polymer particle sizes during polymerization indicates that droplet and aqueous (micellar or both homogeneous) nucleation occurs in the miniemulsion polymerization. With the same concentration of the surfactant used in the miniemulsion polymerization, the polymerization rates of systems with M12B36 are faster than those of systems with M12B12.