The spectroscopic properties of two derivatives of DPH, viz. DPH-N(CH3)(2) and DPH-NO2 (Chart 1), were examined as prospective fluorescence probes. It was found that, contrary to the parent molecule DPH, these two derivatives exhibit fluorescence spectra strongly dependent on the polarity of their immediate environment. It was also found that their fluorescence anisotropy r is as high as that of DPH (r = 0.38). Consequently, DPH-N(CH3)(2) and DPH-NO2 can be used for the simultaneous measurement of micropolarity and microviscosity (or any other property related to r, e.g. phase transition), at the site of their solubilization, in molecular assemblies and microheterogeneous media. Since probing by either one of these two DPH derivatives involves the use of the same probe for the determination of two different microproperties, it is assured that the two microproperties measured correspond to exactly the same microsite, viz. that of the solubilization of the one and only probe. Ordinarily, one uses different probes to determine different microproperties, in which case it is almost certain that these microproperties reflect different sites of the microenvironment. The suitability of these probes for the simultaneous determination of microviscosity and micropolarity has been demonstrated for a number of typical microheterogeneous systems. In all cases the microparameters obtained simultaneously by means of DPH-N(CH3)(2) or DPH-NO2 were at least as good as the ones determined separately by means of well established probes such as pyrene or DPH.