Robert James Selby was born in Brooklyn, New York, the second son of Sydney and Estelle (Mentzer) Selby. His father ran a waterfront food processing plant in Brooklyn and his mother was a homemaker and Red Cross volunteer. Bob's life companion from the age of 15 and his wife, Susan Sorkin Selby, remember spending most of his youth in pool halls, earning pocket money and worrying his mother. When asked about his father's profession, Bob liked to say that he "worked on the sidewalks." Selby's early education was in the New York City public school system. He attended Brooklyn College, from which he received his bachelor's degree in 1961, followed by graduate study as a former National Science Foundation fellow at the University of Chicago, where in 1965 he received his Ph.D. in chemistry. He earned a postdoctoral fellowship in the Air Force Office of Scientific Research, used it to work with Joseph Hirschfelder at the University of Wisconsin for a year, and then (in 1966) joined the faculty at MIT. Selby remained at MIT for the rest of his academic life, serving as chair of the chemistry department from 1990 to 1995, director of the Center for Materials Science and Engineering from 1998 to 2000, and dean of the College of Science from 2000 until 2007.