TEMPO-terminated oligomers of polystyrene (TTOPS) are being used as a macroinitiator to initiate the miniemulsion polymerization of styrene at 125 degreesC. In this work, the surfactant concentration (Dowfax 8390) used to prepare the miniemulsion was varied from 1.25 to 25 mM. It was found that with increasing surfactant concentration the particle size decreased, and the particle number increased as expected. However, this variation in the surfactant concentration and its effect on the number of particles generated had little effect on the resulting polymerization rate and polymer molecular weight in the nitroxide-mediated miniemulsion system. The average numbers of active and stable free radicals per particle were estimated and used to explain the kinetic differences between living free radical miniemulsion polymerization and normal free radical emulsion polymerization.