Quantitative predictions of optical polarizability and its anisotropy are effected through a method that combines intrinsic molecular optical polarizability (as this is determined via semi-empirical quantum calculations) with inter- and intramolecular contributions to molecular optical polarizability (as those are manifested in depolarized Rayleigh scattering experiments). The approach is based on that proposed earlier by Dewar by which one can predict mean optical polarizabilities. Dewar’s methodology is extended to predict not only the mean but also the anisotropy of the optical polarizability. It is shown that the technique is applicable to unsubstituted benzene and a number of substituted benzenes by quantitatively reproducing experimental values of mean optical polarizability and optical anisotropy simultaneously. The technique is further applied to model oligomers of three rigid-rod polymers, cis- and trans-poly(p-phenylene benzobisoxazole) as well as trans-poly(p-phenylene benzobisthiazole), to show excellent agreement with previously published experimental and theoretical results.