Quantitative measures of solvent softness, in the sense of Pearson's hard-softacid-base (HSAB) concept, are considered using three scales: the μ scale, basedon the Gibbs energies of transfer of selected ions, the Raman wavenumber shiftof HgBr2 (the D s scale), and the difference between the IR wavenumber shift ofthe C-I stretch of ICN and the O-H stretch of phenol. Raman and IR bandshifts have been measured for a number of solvents for the neat ones (Raman)and in CCl4 solution (IR). Good linear correlations between the three scalesareobtained that permit the prediction of the softness of a wide range ofsolvents.A number of anomalies encountered are discussed.