Bruce E. Poling is professor of chemical engineering and associate dean of engineering at the University of Toledo (Ohio). He has taught and conducted research for over 30 years in the areas of thermodynamics, physical properties, and process design. John M. Prausnitz is professor of chemical engineering at the University of California at Berkeley. He has extensive physical property experience as a consultant on petroleum, natural gas, petrochemical, cryogenic, and polymeric processes. He is a member of the National Academy of Sciences and the National Academy of Engineering. John P. O'Connell is the Harry Douglas Forsythe Professor of Chemical Engineering at the University of Virginia. He has 35 years of experience in teaching, research, and consulting in physical properties and process design.