Based on expectations from free-volume arguments that the entropy difference between face-on and side-on interface configurations of purely repulsive particles is controlled by the fluid density (or volume fraction) and molecular shape anisotropy, with the entropy difference increasing with increasing density and shape anisotropy (decreasing κ for oblate particles), we have fit the entropy difference at each interface for all systems to a power law with a positive exponent for φ and a negative one for κ. The entropy difference was found to have a quasi-universal power-law dependence on φ /κ at the solid interface and on φ /κ 1/2 at the vapour interface, where φ is the bulk fluid volume fraction and κ is the shape anisotropy, as shown in Fig. , although there is some scatter in the data, particularly for the solid interface. The scaling relationships that best fit the data in Fig. were