Theodore Sorensen was born in Lincoln, Nebraska on May 8, 1928. He studied at the University of Nebraska, receiving a law degree in 1951, being admitted to the Nebraska bar in the same year. For two years, he was an attorney with the Federal Security Agency, until he became assistant to Senator John F. Kennedy in 1953. When Senator Kennedy became President Kennedy, Sorensen was appointed special counsel to the President. Among his duties was working on the President's speeches.
After the end of the Kennedy Administration, Sorensen joined a New York City law firm, later becoming a television commentator. In 1970, he ran for the New York State Senate. Among his writings are Decision Making in the White House (1963), Kennedy (1965) and The Kennedy Legacy (1969).