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Salt-affected soils have been studied extensively with respect to their Na+-Ca2+ exchange properties, hydraulic conductivity and reclaimability. For the most part, these studies have focused on soil environments of the arid west. Recently, however, due to the fact that irrigation has expanded to temperate U.S. regions and to the fact that oil well brines have become an environmental issue in Kentucky as well as elsewhere, there is a need to understand the sodicity and reclaimability of soils that have developed in temperature climates. In this study, two Kentucky soils (Pembroke and Uniontown) have been chosen to evaluate the influence of ionic strength, sodium adsorption ratio, and pH on the Vanselow exchange coefficient (K-upsilon) and adsorbed ion activity coefficients. it is shown that the Pembroke soil has at least two classes of exchange sites and that their Na+-Ca2+ exchange behavior is relatively independent of pH and ionic strength. Furthermore, for the exchangeable sodium percentage (ESP) range of zero to 20, K-upsilon is much greater than one, but decreases in magnitude as ESP increases and then remains constant (ideal solid-solution behavior) approximately one for the ESP range of 20 to approximately 100. On the other hand, the Uniontown soil shows strong Na+-Ca2+ exchange dependency on pH and ionic strength, and furthermore, as pH increases and ionic strength decreases, a strong preference for Na+ over Ca2+ is exhibited. Also a class of exchange sites is exhibited in the ESP range of 0-20, but as ESP extends from 20 to approximately 100, the soil shows a constantly increasing preference for Na+ over Ca2+. Possible causes for the differences in Na+-Ca2+ exchange behavior between these two soils are discussed.