The use of recently developed equations of state for critical phenomena is examined. Deiter's equation is incapable of accurately predicting the gas-liquid critical properties of mixtures of dissimilar size molecules whereas a hard convex body equation does not yield significantly better results than asimple hard sphere equation. In many cases a 'hard sphere + attractive term' equation can predict the critical properties of Type II mixtures to within experimental error. This conclusion is valid for a wide range of component molecules. However, an adjustable parameter is usually required to optimize agreement. Type II liquid-liquid properties can also be accurately calculated but the same precision can not be obtained for Type III phenomena. Some calculations for CHF3 + alkane mixtures are reported which exhibited Type III behavior. In this work the critical properties of CF4+CHF3+CH4 over a wide range of temperature and pressure and calculated. The results illustrate the potential of theory to classify the phase behavior of ternary mixtures.