Bates was born in 1953 in Greenbelt, Maryland, the fourth of eight children to Frances and James Bates. His father was a mathematician, who from 1963–1967 moved the family to Cheltenham, England. Upon returning to the United States, Bob attended DeMatha High School in Hyattsville, Maryland, graduating in 1971, and then went on to Georgetown University, where he pursued a double major in philosophy and psychology, receiving his A.B. in philosophy in 1975. His first job after college was as tourguide for Washington Group Tours, a job he took since it allowed him free time between tours to pursue his writing efforts. In 1977 he met his future wife, Peggy Oriani, whom he married in January 1978, and then founded his own tour company, Potomac Tours. In 1982, with the approach of his 30th birthday, he sold the company to spend two years writing a novel, though did not finish. It was around this time that Bates' father gave his old TRS-80 computer to his son, to help with the novel-writing. With the computer, Bates received a copy of the interactive fiction game "Zork", and immediately fell in love with the genre, seeing it as a way that he could pursue a writing career, making games.