In 1923 he began his teaching career in Tufts College. In 1924 he received a Ph.D. from Harvard and did graduate work at the University of Berlin. Returning to the United States, he became an instructor of psychology in 1924 and an assistant professor in 1926 at Princeton University. In 1927, he joined the faculty of Brown University as an associate professor of psychology and, in 1928, was promoted to the rank of full professor in the same subject, a chair he held until 1936, when he became chairman of the department of psychology and dean of the faculty of arts and sciences at Rochester University. Two years later he returned to Tufts to act as president of the college and as director of the laboratory of sensory psychology and physiology. He was also a visiting professor at Harvard, Radcliffe, and other colleges. During World War II, Carmichael held a number of public offices, including membership in an emergency committee in psychology for the National Research Council (1940), in a committee on selection and training of aircraft pilots, and in a committee on service personnel, selection, and training. He was chairman of the council's division of anthropology and psychology (1941-1945). On April 9, 1952, he resigned from the presidency of Tufts College to accept an appointment as secretary of the Smithsonian Institution in Washington, D.C. He left the Smithsonian in 1964 to become vice-president for research and exploration at the National Geographic Society, where he sponsored the work of such people as anthropologist Louis S. B. Leakey and underseas explorer Jacques-Yves Cousteau.