Eagleton was born in St. Louis, Missouri, the son of Zitta Louise (Swanson) and Mark David Eagleton, a politician who had run for mayor. His paternal grandparents were Irish immigrants, and his mother had Swedish, Irish, French, and Austrian ancestry. Eagleton graduated from
St. Louis Country Day School, served in the U.S. Navy for two years, and graduated in 1950 from
Amherst College, where he was a member of
Delta Kappa Epsilon fraternity (Sigma chapter). He then attended
Harvard Law School. After graduating in 1953, Eagleton practiced law at his father's firm and later became associated with
Anheuser-Busch's legal department. Eagleton married Barbara Ann Smith of St. Louis on January 26, 1956. A son, Terence, was born in 1959, and a daughter, Christin, in 1963. He was elected circuit attorney of the City of St. Louis in 1956. During his tenure, he appeared on the TV show ''
What's My Line?'' (episode #355) as "District Attorney of St. Louis". (He stumped the panel.) He was elected Missouri Attorney General in
1960 at age 31 (the youngest in the state's history). He was elected the 38th lieutenant governor of Missouri in
1964, and won a U.S. Senate seat in
1968, unseating incumbent
Edward V. Long in the Democratic primary and narrowly defeating Congressman
Thomas B. Curtis in the general election. Eagleton suffered from depression; he checked himself into hospital three times between 1960 and 1966 for physical and nervous exhaustion, receiving
electroconvulsive therapy (shock therapy) twice. He later received a diagnosis of
bipolar II from
Frederick K. Goodwin. The hospitalizations, which were not widely publicized, had little effect on his political aspirations. The
St. Louis Post-Dispatch noted in 1972, immediately after Eagleton's vice-presidential nomination: "He had been troubled with gastric disturbances, which led to occasional hospitalizations. The stomach troubles have contributed to rumors that he had a drinking problem." ==1972 vice-presidential candidacy==