The behavior of the stable free radical moderated polymerization of styrene in the presence of 2-fluoro-1-methylpyridinium p-toluenesulfonate (FMPTS) has been examined. The rate enhancement has been found to be the result of the decrease of free nitroxide (TEMPO) concentration that shifts the equilibrium between capped and growing chains toward the growing free radical form. The decrease in TEMPO concentration was shown to be coupled to the presence of FMPTS. The system is sensitive to the initiator employed and the timing of the addition of FMPTS. If the polymerization rate change due to the change in TEMPO concentration is accounted for, a secondary polymerization retarding influence of FMPTS was observed.