Isobaric vapor-liquid equilibrium (VLE) data for the sec-butyl acetate + acetic acid binary system, as well as the sec-butyl acetate + acetic acid + water ternary system, were measured at 101.33 kPa using a modified Rose still. The second virial coefficients and apparent fugacity coefficients were calculated to analyze the nonideal behavior in vapor phase caused by the association of acetic acid, which were corrected by the chemical theory and Hayden-O'Connell method. The binary experimental data were tested for thermodynamic consistency by the Herington method and the point-to-point test and correlated by the nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) models using the nonlinear least-squares method. The model parameters of the binary system were used to correlate the ternary VLE data. The ternary correlated values obtained in this way agreed well with the experimental values.