William D. McCain Jr. has been a visiting professor in the Department of Petroleum Engineering at Texas A&M University since 1991. He also has a petroleum consulting firm, McCain Engineering. McCain started his engineering career with Esso (now Exxon) Research Laboratories in 1956. He was professor and head of the petroleum engineering department at Mississippi State University from 1965 to 1976. He taught petroleum engineering at Texas A&M University from 1984 through 1987. McCain was a consulting petroleum engineer with Cawley, Gillespie & Associates from 1987 until 1991. He was then with S.A. Holditch & Associates from 1991 until 2000, retiring as executive vice president, chief engineer, and member of the board of directors. His engineering specialties within the company were properties of petroleum fluids and reservoir engineering, especially for gas condensates and volatile oils. He holds four US patents, has published more than 60 technical articles, wrote two editions of The Properties of Petroleum Fluids (PennWell) and was coauthor of Petroleum Reservoir Fluid Property Correlations (PennWell). He holds a BS degree from Mississippi State College and MS and PhD degrees from Georgia Institute of Technology, all in chemical engineering. He is also a graduate of the US Army War College.