The activities of methanol, ethanol, 2-propanol, and 1-butanol in poly(vinylpyrolidone) (PVP) (weightaverage relative molar mass, M-w = 10 000) solutions have been measured by the isopiestic method at 25 degreesC. Sodium iodide and calcium chloride were used as the isopiestic standards for the calculation of activities. A polynomial equation, the original Flory-Huggins equation, and the modified Flory-Huggins equation with concentration-dependent interaction parameters have been used for the correlation of the experimental solvent activity data. The strength of interaction between different alcohols and the polymer was discussed on the basis of the obtained Flory-Huggins interaction parameters.