Few Presidents were as dedicated to their family as Harry S. Truman. Although his father died in 1914, Truman’s mother, Martha Ellen, lived into her nineties—long enough to see him succeed President Franklin D. Roosevelt. “Mama,” as Truman called his mother, passed away in 1947. She and her son had a very close relationship. A devoted Democrat and an astute political observer, she avidly supported her son's political career. In 1944, she chaired the first meeting of the female women workers in his campaign for the vice presidency. Truman corresponded regularly with his mother, often revealing in wonderfully expressive language his innermost thoughts about political affairs and family.

Truman's younger sister Mary Jane and brother Vivian were always close to him. Mary Jane, having never married, lived at home with "Mama" Truman and thus shared in all the news and attention that came their way. Vivian, who worked as the district director of the Federal Housing Administration, kept Truman apprised of political news from Missouri. The President often consulted his brother before making patronage decisions involving Missourians.

Truman was a doting and protective father to his daughter Mary Margaret. When Truman moved to Washington to serve in the Senate, Margaret was ten-years old. Thereafter, she would live half the year in Independence and half in Washington, until she was in high school. During the White House years, Margaret attended George Washington University. After graduating, she pursued a career as a vocalist.

Margaret performed frequently in public—she even went on a successful thirty-city tour in 1947—and showed some promise. Music critics, however, did not always offer good reviews of her performances. As a father, Truman could not abide the criticism, although he almost never responded publicly. On one particularly stressful occasion in December 1950, at the low point of the Korean War, his anger got the best of him. After reading a poor review of Margaret's performance in the Washington Post, Truman wrote the author: "Some day I hope to meet you. When that happens you'll need a new nose, a lot of beefsteak for black eyes, and perhaps a supporter below!" A public uproar ensued after the reviewer released Truman's note to the press. Truman, though, maintained that the public understood he was just protecting his daughter, like any good father. Margaret finally gave up her quest for a musical career to marry Clifton Daniel, a highly successful New York newspaper editor, in 1956. They eventually had four children.

Harry Truman's life in the White House followed a regular routine. Truman usually awoke at 5:00 in the morning, dressed, and took a vigorous one or two-mile walk (at the Army's 120-steps-per-minute pace) around the White House grounds and neighborhood - wearing a business suit and tie! After an assassination attempt in 1950, the Secret Service took the President to various undisclosed locations for his daily walk. He then had a rubdown, a shot of bourbon, and a light breakfast. He tried to lunch each day with Bess and take short afternoon naps. At mid-day, Truman often took a few laps in the White House swimming pool, swimming with his eyeglasses on. In the evening, if no business was at hand, he and Bess would enjoy a cocktail, eat dinner, and then listen to music or watch a movie. Once or twice a week, he would slip away to a stag poker party with his male friends at a private home, seldom returning before midnight. Truman loved to tell and hear dirty jokes, and enjoyed visiting with and pulling strings for his old Army friends. He also relaxed by taking trips aboard the presidential yacht Williamsburg or by vacationing at the naval base in Key West, Florida. Truman almost always invited his male friends—and rarely Bess or Margaret—along on these excursions.