Vapor-liquid-equilibrium (VLE) data for several copolymer + solvent systems at 298.15 K and 308.15 K have been obtained using the classical gravimetric-sorption method. The solvents studied were benzene and toluene. The copolymers studied were poly(styrene-co-methyl methacrylate), poly(styrene-cobutadiene), and poly(n-butyl methaerylate-co-N,N-dimethylaminoethyl methacrylate). The molecular thermodynamic model based on a close-packed lattice model developed by Hu et al. was used to correlate the experimental data.