Measurements of the densities have been made with a vibrating tube densimeter over the whole composition range for sulfolane + ethylbenzene and sulfolane + 1-methylnaphthalene at 313.15 and 333.15 K and water + N,N-dimethylformamide, water + methanol, water + N-formylmorpholine, and water + N-methylpyrrolidone at 283.15 and 313.15 K. Excess molar volumes (V-E) calculated from the measured densities show negative deviation from the ideal for these systems. For water + methanol and sulfolane + ethylbenzene, the values of V-E increase with increasing temperature, but for other systems, the values of V-E decrease with increasing temperature. The values of V-E were fitted to the polynomial function and correlated by means of the Peng-Robinson equation.