In an earlier article, a Corresponding States Method was presented for predicting the saturated liquid densities of both pure components and mixtures. The method is based on the known saturated liquid densities of two reference fluids and requires the critical properties and acentric factors of the pure components as input parameters. We use the method here to calculate the swelling factors of CO2-crude oil mixtures using CO2 and n-dodecane as the reference fluids. The critical properties and acentric factors of the crude oils were estimated from their API gravities and Watson K-factors. Using only one adjustable coefficient to characterize each CO2-crude oil system, swelling factors were calculated to within 0.5% of their experimental values. The single, adjustable coefficient is linearly related to the boiling point of the crude.