The solvent-induced UV-vis spectral shifts in 4-nitroanisole and pyridinium N-phenoxide betaine-30 dyes utilized in the famous pi* and E(T)(30) polarity scales, respectively, are analyzed by molecular theories in terms of long-range solute-solvent interactions due to induction, dispersion, and dipole-dipole forces. The solvent-induced shift is represented as a sum of the differential solute-solvent internal energy and the differential energy of binding the solvent molecules in the solute vicinity. The aim of the study is 3-fold : (i) to clarify and quantify the relative effects of the three types of interactions, (ii) to elicit the magnitude of the effect of specific forces, and (iii) to evaluate the contribution of the differential solvent binding to the spectral shift. For (i), the dye properties directing the weighting are the size and the differences in both polarizability and dipole moment between ground and excited states. : (i) to clarify and quantify the relative effects of the three types of interactions, (ii) to elicit the magnitude of the effect of specific forces, and (iii) to evaluate the contribution of the differential solvent binding to the spectral shift. For (i), the dye properties directing the weighting are the size and the differences in both polarizability and dipole moment between ground and excited states. : (i) to clarify and quantify the relative effects of the three types of interactions, (ii) to elicit the magnitude of the effect of specific forces, and (iii) to evaluate the contribution of the differential solvent binding to the spectral shift. For (i), the dye properties directing the weighting are the size and the differences in both polarizability and dipole moment between ground and excited states.