Osmolytes such as Trimethylamine n-oxide (TMAO) are known to confer stability to proteins, as well as counter some of the effects of denaturants such as urea. Since there are several cosolvent contributions to this stabilizing effect, the different mechanisms are difficult to elucidate. Our approach to this problem was to look at how the macroscopic interfacial free energy of a chemically functionalized surface depends on the composition of the aqueous osmolyte solutions. The interfacial free energy was determined using a chemical force microscope (CFM), where both the probe and substrate surface was chemically functionalized. We have determined how aqueous solutions of several commonly used osmolytes affected the interfacial free energy of self-assembled monolayers (SAMs) with either aromatic or aliphatic terminal groups. These results will be critically compared to previous studies of the denaturants urea and guanidinum chloride on the same SAMs. The relative importance of the interfacial free energy to the stabilizing energy of osmolytes will be evaluated.