Solutions in which one of the components is a high polymer and the other component is a small-molecule solvent behave in a markedly different manner than do solutions of low molecular weight components. For example, the latter obey Raoult's law if the heat of mixing is negligible; however, many polymer solutions show pronounced deviation from ideality even at concentrations of one percent or less (Figures 1–7). These deviations are due to enthalpy and entropy effects which arise from large differences in size between solvent and solute molecules. Ability to predict the solubility characteristics of polymer/solvent systems, and to calculate values of the colligative properties of such systems, is important in engineering studies of polymer processes. This paper presents a compilation of data which can be used in conjunction with the Flory-Huggins theory of polymer solutions to predict properties of polymer solutions. A method is given for predicting polymer/solvent interaction parameters (μ) for systems for which experimental data are not available. Also included is a comparison between the proposed method and two other semiempirical methods for predicting μ.