The solubilities of five solutes, biphenyl, naphthalene, fluorene, phenanthrene, and acenaphthene, In pure benzene and cyclohexane and In mixtures of benzene and cyclohexane, have been determined. The activity coefficients of the five solutes In cyclohexane are correlated to within an average of 0.6% by Wilson's equation compared to 9.3 % by the Scatchard-Hlldebrand expression. Similarly for the solutes In benzene, the activity coefficients were correlated to within an average of 0.5 % and 1.2%, respectively, by the same two methods. For the ternary mixtures Wilson's method correlates the activity coefficients for the 78 measured data points within 1.4% compared to 2.6% by the Scatchard-Hlldebrand expression. As expected, when the solution exhibits a significant deviation from Ideal behavior, regular solution theory becomes Inadequate and Wilson's equation Is proposed as a more appropriate correlation. The solubility data can also be correlated as functions of reduced temperature T"/T where 7m Is the melting point temperature.