The thermodynamic properties of solutions containing acetonitrile and one of the propanols have been correlated with an extended model which assumes the self-association of acetonitrile and the propanol and complex formation between acetonitrile and the propanol, with an allowance for non-polar interactions. Vapor-liquid and liquid-liquid equilibrium and excess enthalpy data for ternary mixtures including acetonitrile, the propanol, and a non-associating component have been successfully predicted by use of the model with only the parameters obtained from constituent binary mixtures.