The limited partition coefficient data presently available on amphiphilic compounds precludes the serious testing of the HOR concept, especially any correlation that it may have with HLB. The HLB scale, on the other hand, has been evolved for complex amphiphile mixtures rather than pure amphiphiles, further complicating the development of a correlation between HLB and other amphiphile-system properties. The paucity of reliable data, then, on the partition coefficient, EACN concept and HLB, especially with respect to reasonably well defined amphiphiles, greatly impedes progress in the development of a rational basis relating surfactant function to molecular structure. The effect of oil, however, in the oil-water-amphiphile system might be assessed through use of the solubility parameter concept since the original HLB scale was based on the stability of a specific oil-water emulsion. Thus, while the physico-chemical methods exist to quantitatively establish surfactant-wateroil behavior and to test current theories and correlations, progress in this area must await the cataloging of reliable physicochemical data on reasonably well defined amphiphiles.