Based on the valence bond-charge transfer model for push-pull polyenes and reaction field theory, several parameter-dependent relations for selecting the molecule-solvent pair that produces a maximum value of the nonlinear optical response have been established. From these relations, we have determined a limit to the value of the dielectric constant of the solvent (above ε = 9) and effectiveness of the donor-acceptor pairs (between 5 and 6eV) beyond which the (hyper)polarizabilities of push-pull molecules in solution do not exhibit any significant change in magnitude. © 2003 Taylor & Francis Group, LLC.