Frequency-dependent differential polarized phase and modulation data were used to measure time-dependent anisotropy decays of 9-aminoacridine and Y-base. The data were obtained at various excitation wavelengths, at which the fundamental anisotropies (r0) varied from -0.17 to 0.373. The different values of r0 result in different contributions of the multiple correlation times to the anisotropy decay. The multi-wavelength data were analyzed globally, revealing both molecules to be anisotropic rotators. The rotational motions of Y-base are more anisotropic than those of 9-aminoacridine. In propylene glycol at -5 ° C the two correlation times for Y-base were found to be 2.1 and 12.1 ns. For 9-aminoacridine the correlation times were 9.5 and 14.1 ns.