The Holten-Andersen equation of state and the UNIFAC-FV (Free Volume) activity coefficient models are compared using a polymer solution data base. Both the Holten-Andersen equation of state and the UNIFAC-FV models have a foundation in the equation of state developed by Flory for polymer solutions. The Holten-Andersen equation of state is presented here with some corrections from the original publication. The UNIFAC-FV model is an extension of the UNFAC model for polymer solutions and includes the free volume expression from the Flory equation of state. The Holten-Andersen group contribution equation of state and the UNIFAC-FV activity coefficient model are the only predictive models available that were developed specifically for polymer solutions. Unlike the older correlative methods, these two models have not been previously tested and compared using an experimental data base.