Vapor-Liquid-equilibrium (VLE) data are reported for binary mixtures of arborescent polystyrene or linear polystyrene dissolved in chloroform, toluene, or cyclohexane in the range 50-70 degrees C. Using a classic gravimetric-sorption method, the amount of solvent absorbed by the polymer was measured as a function of solvent vapor pressure. VLE data are compared to osmotic second-virial-coefficient data for similar arborescent and linear polystyrenes. Solvent activity depends on the arborescent polystyrene generation number in cyclohexane solutions but similar dependence on arborescent polystyrene generation number is not observed for polymers dissolved in chloroform or toluene.