Vapor-liquid equilibrium data were measured for the systems CO2-ethylbenzene and CO2-styrene over a pressure range from 14 to 85 atm at 308, 318, and 328 K. Vapor-liquid equilibrium data were also measured over the same pressure and temperature ranges for the system CO2-ethylbenzene-styrene, where the ratio of styrene to ethylbenzene in the liquid phase was kept at 1.86.