Russell Lincoln Ackoff (12 February 1919 - 29 October 2009) was one of the 20th century's foremost organizational theorists, a respected consultant and Anheuser-Busch Professor Emeritus of Management Science at The Wharton School, University of Pennsylvania. He completed his undergraduate studies in Architecture at the University of Pennsylvania in 1941. From 1942 to 1946 he served in the US Army, stationed in the Philippines. He returned to study at the University of Pennsylvania, where he received his doctorate in philosophy of science in 1947, as C. West Churchman's first doctoral student, and also taught logic. From 1967 onwards, he received a number of honorary doctorates. His career in Operations Research began at the end of the 1940s. His 1957 book Introduction to Operations Research, co-authored with C. West Churchman and Leonard Arnoff, helped to define the field. Ackoff was president of the Operations Research Society of America in 1956-1957 and president of the International Society for the Systems Sciences in 1987. A founding member of the Institute of Management Sciences, his work in consulting and education involved more than 350 corporations and 75 government agencies in the United States and beyond. Management grandee, he was voted one of the world's most influential business thinkers in a recent poll by the Harvard Business Review.