Russell L. Ackoff was often called the Dean of America's Systems Thinking community. He was an organizational theorist, consultant, and Anheuser-Busch Professor Emeritus of Management Science at the Wharton School, University of Pennsylvania. Ackoff was a pioneer in the field of operations research, systems thinking and management science. Dr. Ackoff helped establish the field of operations research in the 1950's and was president of the Operations Research Society of America (ORSA) in 1956–1957. His book, "Introduction to Operations Research," co-authored with C. West Churchman and Leonard Arnoff, John Wiley & Sons, (1957), was a pioneering work in the field. From 1964 to 1986, Dr. Ackoff was professor of systems sciences and professor of management science at the Wharton School at the University of Pennsylvania. Dr. Ackoff characterizes human-created systems as "purposeful systems," whose members are also purposeful individuals who intentionally and collectively formulate objectives and are parts of larger purposeful systems. The fact that human-created systems are experiencing profound change today can be attributed to the end of the Machine Age and the onset of the Systems Age. Systems Thinking teaches that knowledge and understanding of the aims of human-created, purposeful systems can only be gained by taking into account the mechanisms of social, cultural, and psychological systems involved in their creation. Dr. Ackoff has authored or co-authored 31 books and 250 articles, and has conducted research for more than 300 corporations and government agencies. His most recent book is Turning Learning Right Side Up: Putting Education Back on Track", co-authored with Daniel Greenberg, Wharton School Publishing (2008). Other key books are "Re-Creating the Corporation: a design of organizations for the 21st century," Oxford Univ. Press (1999) and "Redesigning Society," with Sheldon Rovin, Stanford Univ. Press (2003). Dr. Ackoff died unexpectedly Thursday, October 29, 2009, after complications of hip replacement surgery.