Daniel Charles Drucker was an authority on the theory of plasticity in the field of applied mechanics. He was awarded the Timoshenko Medal in 1983. He was known throughout the world for contributions to the theory of plasticity and its application to analysis and design in metal structures. Dan Drucker was born in New York City on June 3, 1918. Drucker received his B.S., M.S., and Ph.D. degrees from Columbia University. He taught at Cornell University from 1940 to 1943 before joining the Armour Research Foundation. After serving in the US Army Air Corps, he returned to the Illinois Institute of Technology for a short time before he went in 1947 to Brown University, where he did much of his pioneering work on plasticity. In 1968 he joined the University of Illinois as dean of engineering. During his more than 15 years there the College of Engineering was consistently ranked among the best five in the nation. The college was known for both its insistence on technical excellence and its commitment to equal opportunity for all. Dan left Illinois in 1984 to become a graduate research professor at the University of Florida, from which he retired in 1994. In 1988 he received the National Medal of Science. He was a member of the National Academy of Engineering and of the American Academy of Arts and Sciences, and a foreign member of the Polish Academy of Sciences. He also had honorary doctorates from the Technion; Lehigh, Brown, and Northwestern Universities; and the University of Illinois at Urbana-Champaign.