Robert S. Mulliken (June 7, 1896 – October 31, 1986) was an American physicist and chemist who received the Nobel Prize for Chemistry in 1966. He was a distinguished member of the faculty at the University of Chicago for 55 years. Mulliken was primarily responsible for the early development of molecular orbital theory (the elaboration of the molecular orbital method of computing the structure of molecules). His father was Samuel Mulliken, a professor of organic chemistry at MIT. He graduated from high school in 1913 and received the same scholarship to MIT that his father had won. After graduation from MIT in 1917, he was drafted into the Army during World War I. After the war, he entered the Ph.D. program at the University of Chicago and studied under Nobel Prize-winning physicist Robert A. Millikan, which exposed him to the old quantum theory. He then went to Harvard and was able to associate with many future luminaries, including J. Robert Oppenheimer and Harold C. Urey. In 1925 and 1927, Mulliken traveled to Europe and worked with quantum theorists Paul A. M. Dirac, Werner Heisenberg, Erwin Schrodinger, Max Born, and Friedrich Hund, who were developing the new quantum mechanics that would eventually supersede the old quantum theory. In 1927, Mulliken worked with Hund and developed a molecular orbital theory, now referred to as the Hund-Mulliken theory. He returned to the University of Chicago and was promoted to full professor of physics and chemistry in 1931. Robert Mulliken became a member of the National Academy of Sciences in 1936, the youngest member in the organization’s history, at that time. Professor Mulliken participated in the 1983 Achievement Summit in Coronado, California and spoke to the student delegates about the joy of scientific research.