Maurice Bourrel is a Research Scientist at Elf-Aquitaine in Artix, France. The author or coauthor of some 30 papers, he has studied surfactants, microemulsions, and enhanced oil recovery for many years. Dr. Bourre! received the doctorate (1974) in physics from the University of Pau in France and the "Doctorat d'Etat" (1988) at the University of Bordeaux in France. Robert S. Schechter holds the Getty Oil Company Centennial Chair in Petroleum Engineering, and is also Professor of Chemical and Petroleum Engineering, at the University of Texas at Austin, where he has taught since 1956. He has published more than 185 papers, primarily on colloid and interface science. His research on surfactants has included extensive work on mixed micelles, the relationship between the structure of surfactants and microemulsion phase behavior, thermodynamics of microemulsions, stability of macroemulsions, and interfacial rheology. Among the many honors he has received are membership in the national Academy of Engineering and the Order of Palmes Academiques awarded by the French government in 1978. He his a member of the American Chemical Society, American Institute of Chemical Engineers, Society of Petroleum Engineers, and American Institute of Mining Engineers. Professor 5chechter earned the B.5. degree (1950) at Texas A & M University and Ph.D. degree (1956) in chemical engineering at the University of Minnesota.