Densities, refractive indices, and speeds of sound at 298.15 K and isobaric vapor-liquid equilibria data at 101.3 kPa are reported for the binary mixtures containing methanol + vinyl propionate and vinyl acetate + vinyl propionate. Excess molar volumes, refractive index deviations, and changes of speeds of sound upon mixing were calculated from the measured data and fitted to Redlich-Kister polynomials. Vapor-liquid equilibrium (VLE) experimental data were tested for thermodynamic consistency by means of a modified Dechema test and were demonstrated to be consistent. The activity coefficients were correlated with the Margules, van Laar, UNIQUAC, NRTL, and Wilson equations with two suffixes and the Wilson model with three-suffix equations. The ASOG model also was used for prediction. The methanol (1) + vinyl propionate (2) system shows an azeotrope at x(1) = 0.825. Experimental vapor pressures of vinyl propionate are also included, and the Antoine constants were determined.