Isentropic compressibilities of four ternary mixtures (1,3-dichlorobenzene + methyl ethyl ketone + l-propanol, + l-butanol, + l-pentanol, and + 1-hexanol) were determined from speed of sound measurements at 303.15 K. The deviation in isentropic compressibility was also computed. The deviation is, in general, negative for all mixtures. Speed of sound data were compared with those predicted by free length theory and collision factor theory. The predictive expressions give a rough estimate of the property for all the mixtures.