Fluorescence depolarization of a squaraine dye (HSq, bis[4-(dimethylamino)phenyl] squaraine) was studied in pure viscous solvents triacetin (glycerol triacetate) and ethylene glycol. In ethylene glycol, the hydrodynamic friction given by the Stokes-Einstein equation accounts for the observed results; in triacetin, the dielectric friction becomes important because of the slow dielectric response of the liquid. Average rotational relaxation times were calculated from fluorescence anisotropy measurements within reversed micelles with water, glycerol, and formamide as the entrapped polar solvents, and the variation in the trend with the amount of each polar solvent (w(o), g(o), or f(o)) is quite different. The results are interpreted by comparison with those obtained in pure viscous solvents and show the contribution of the dielectric friction in aqueous reversed micelles. In glycerol reversed micelles, the importance of both the dielectric and hydrodynamic friction is shown. In formamide reversed micelles, the inner pool appears immobilized. The dye rotation dynamics is affected by the location of the inner pool, which in turn reflects the dielectric interactions with the media. The dye partition between different interfacial sites was assessed by steady and transient-state (picosecond time scale) fluorescence measurements.