Ford was born July 13, 1942 at Chicago, Illinois's Swedish Covenant Hospital, to Dorothy (née Dora Nidelman), a homemaker and former radio actress, and Christopher Ford (born John William Ford), an advertising executive and a former actor. A younger brother, Terence, was born in 1945. Ford's paternal grandparents, John Fitzgerald Ford and Florence Veronica Niehaus, were of Irish Catholic and German descent, respectively. Ford's maternal grandparents, Harry Nidelman and Anna Lifschutz, were Jewish immigrants from Minsk, Belarus (at that time a part of the Russian Empire). When asked in which religion he was raised, Ford has jokingly responded, "Democrat". He has also said that he feels "Irish as a person, but I feel Jewish as an actor".
Ford was active in the Boy Scouts of America, and achieved its second-highest rank, Life Scout. He worked at a scout camp, Napowan Adventure Base, as a counselor for the Reptile Study merit badge. Because of this, he and Eagle Scout director Steven Spielberg later decided that the character of young Indiana Jones would be depicted as a Life Scout in the film Indiana Jones and the Last Crusade. They also jokingly reversed Ford's knowledge of reptiles into Jones's fear of snakes.
In 1960, Ford graduated from Maine East High School in Park Ridge, Illinois. His was the first student voice broadcast on his high school's new radio station, WMTH, and he was its first sportscaster during his senior year (1959–1960). He attended Ripon College in Wisconsin, where he was a member of the Sigma Nu fraternity. He took a drama class in his junior year, chiefly as a way to meet women. Ford, a self-described "late bloomer", became fascinated with acting.