A nontraditional picture for primary kinetic isotope effects (KIEs) is presented for proton transfer (PT) reactions in a polar environment in the proton adiabatic regime, in which proton motion is quantum mechanical, but is not tunneling. The description differs from the "standard" treatment of KIEs for PT in both the quantization of the proton nuclear motion and the identification of a solvent coordinate as the reaction coordinate. KIEs resulting from a free energy relationship (FER) based on this adiabatic PT description recently derived (Kiefer, P. M.; Hynes, J. T. J. Phys. Chem A 2002, 106, 1834,1850) are presented. It is shown that key experimental consequences thought to validate the standard picture for KIEs also follow from this nontraditional picture, including those for (i) Arrhenius temperature behavior, (ii) dependence on reaction asymmetry DeltaG(RXN), (iii) the magnitude of the KIE, and (iv) the Swain-Schaad relationship. A detailed comparison between the present picture and the standard description is presented.