It is shown that the radiative decay rate of the fluorescent state of 1,1’-dinaphthylamine decreases, while that of 2,2’-dinaphthylamine remains unchanged, as the polarity of the solvent is increased. These results, which are in accord with the predictions of INDO 1/S-CIS calculations, provide strong support to the conclusion that the lowest excited singlet state of the dinaphthylamines is an intramolecular charge-transfer state in solvents of high dielectric constants. The INDO 1/S method appears to be a reliable tool for investigating intramolecular charge transfer in these and related diaryl compounds.