To discuss prediction of vapor-liquid equilibria with esterification on the basis of the ASOG model, infinite-dilution binary activity coefficients were measured for five systems in the 40°-100°C range by an ebulliometric method. The systems measured are methyl acetate-n-heptane, ethyl acetate-ethanol, ethyl acetate-water, acetic acid-n-heptane, and acetic acid-ethyl acetate. The group Wilson parameters for any system made up of CH2, OH, COO, COOH groups were determined in the 40°-100°C range by infinite-dilution activity coefficients. Vapor-liquid equilibria predicted for three quaternary esterification systems and for 26 binary and ternary systems involving alcohols, water, paraffins, esters, and carboxylic acids agreed fairly well with observed values.