The application of computational techniques to medicinal chemistry is growing at a tremendous rate. Quantitative structure-activity relationships (QSAR), which relate biological and toxicological activities to structural features, have been employed widely to correlate structure to activity. A difficulty of this approach has been nonuniformity of parameter sets and the inability to examine contributions across properties and data sets. Linear solvation energy relationships (LSER) developed by Kamlet and Taft circumvent many of the difficulties and successfully utilize a single set of parameters for a wide range of physical, chemical, and biological properties. We have replaced the LSER solvato-chromatic parameters with theoretically determined parameters to permit better a priori prediction of properties. Comparison of the two parameter sets for five biological activities is presented, showing the excellent fit of the theoretically determined parameters.