It has been demonstrated in this paper that polarizabilities of organic molecules at their optical absorption regions can be extracted from the experimental data of the enhanced reflection for s-polarized electromagnetic radiation caused by a submonolayer of organic molecules physisorbed on quartz surface. Experiments have been carried out with Rhodamine-6G and D289 molecules. For each molecule, the polarizability increases dramatically in the wavelength region where the electronic transition takes place. For Rhodamine-6G, the polarizability is about 980 Angstrom(3) at its peak absorption wavelength 530 nm, and for D289, the value is about 392 Angstrom(3) at its peak absorption wavelength 470 nm. The perfect match between the reflection and transmission spectra of Rhodamine-6G indicates that the polarizability of a molecule at its absorptive region is proportional to its molar absorptivity. (C) 1997 American Institute of Physics.