To shed more light on the factors that promote micelle growth and induce the sphere-to-rod transition, three micellar systems formed by surfactants containing tetradecyltrimethylammonium (TTA(+)) as cation and ortho-, meta-, or para-fluorobenzoate as counterion were investigated by conductivity, surface tension, and H-1, F-19, and C-13 NMR spectroscopy. The investigations illustrate that the transfer of TTA(+)/fluorobenzoate surfactants into the micellar phase and micelle growth are accompanied by characteristic changes in the NMR chemical shift and conductivity data, which were analyzed to determine the critical micelle concentration (cmc), the region of predominately spherical micelles, and the region of growth, where spherical aggregates are transformed to rodlike micelles. The studies reveal that TTA(+)/ortho-fluorobenzoate micelles with an averaged cmc of 2.51 mM remain roughly spherical even at surfactant concentrations as high as 70 mM. The graphs, in which the specific conductivity is plotted versus increasing surfactant concentration or in which the chemical shifts of the ortho-fluorobenzoate or the TTA(+) resonances are plotted versus increasing or the inverse of increasing surfactant concentration, give rise to a single breakpoint at the onset of micellization. In contrast, the NMR and conductivity plots of TTA(+)/meta- and para-fluorobenzoate micelles with averaged cmc values of 1.29 and 1.38 mM, respectively, show two breakpoints, one at the cmc and one at total surfactant concentrations 10 times the cmc. This second cmc indicates that TTA(+)/meta- and para-fluorobenzoate micelles change shape and grow from roughly spherical to rodlike aggregates at higher surfactant concentration. The NMR data reveal that aggregate growth is not an abrupt but a rather continuous process and that the positioning of the benzoate ions at the micellar interface along with their reduction of headgroup repulsions are the major contributors to micelle growth. The meta- and para-fluorobenzoates intercalate among the N+(CH3)(3) headgroups thereby forming tight ion pairs, reducing headgroup repulsions, and inducing growth. Contrary, the ortho- fluorobenzoate ions penetrate the micellar interface more deeply and move toward the palisade layer. This positioning does not enable the anions to reduce effectively the unfavorable electrostatic headgroup interactions, and as a result, TTA(+)/orthofluorobenzoate micelles remain spherical even at high surfactant concentrations.