Even before she became First Lady, Edith Kermit Carow Roosevelt was used to the demands of public life. Her husband, Theodore, had held many political positions during their marriage, including the governorship of New York. And as much as he courted the press and enjoyed public attention, Edith sought to avoid publicity and keep her family out of the public eye. As First Lady, however, she accepted her role and made lasting changes to the institution. When her husband suddenly became President in September 1901, Edith first turned her attention to the White House itself. With six children ranging from four to seventeen, she wanted the presidential mansion to be a comfortable family home, an office for her husband, and a historical showcase for the nation. Its present dimensions, however, were too small to accommodate that vision. She approached the architectural firm of McKim, Mead, and White to design renovations that would separate the family living quarters from the executive offices, remove the Victorian additions, and restore the mansion to its original 18th-century Federal appearance. Impressed with the architectural plans, Congress appropriated money for the renovations, which included remodeling the East Wing to enlarge the First Family's living quarters and add guest rooms; a new West Wing for executive offices; upgrading the original plumbing, heating, and lighting; enlarging the State Dining Room; and redecorating the Green Room, Blue Room, and East Room with period antiques.

An enhanced State Dining Room meant that Edith had to purchase new china for the large dinner parties she would be hosting. She therefore ordered a Wedgwood service for 120 people. Interest in her own china fostered a curiosity about the services of previous First Ladies. Edith arranged for the china from the past twenty-five administrations to be displayed in cabinets along a ground floor hallway where guests stood in line to meet the first couple. Guests could also gaze upon the faces of former First Ladies, as Edith collected the portraits of her predecessors and had them displayed prominently in the same corridor. Mrs. Roosevelt revealed the White House renovations to an enthusiastic public during the 1903 New Year's Day reception. As First Lady, Edith directed a full social schedule. She hosted the wives of the cabinet officers who, as a group, tried to govern the moral conduct of Washington society through their guest lists. Edith also used her "cabinet meetings" to release her schedule of entertainments so that she would not be upstaged. She hosted visiting royalty, attended cabinet dinners, greeted guests at New Year's receptions, and offered weekly musicales featuring both amateur and famous performers. The two most significant social events during her tenure were the wedding of her stepdaughter, Alice Roosevelt, and the society debut of her daughter, Ethel Roosevelt.

To help her run the White House, she hired a chief usher to monitor household details and the domestic staff, and employed caterers to fix and serve meals. She was also the first First Lady to employ a full-time, salaried social secretary to handle scheduling, social affairs, and correspondence. But Edith's main focus was on being "Mrs. Roosevelt," a title she preferred to that of "First Lady." To that end, she encouraged Teddy Roosevelt to take time from his busy work schedule to rest and relax with the family. When she thought the presidency was wearing down her husband, Edith considered ways to alleviate his burden. Although the family went to their house, Sagamore Hill, in New York during the summer, the press and politicians frequently followed them there, making these retreats something of a working holiday for Theodore. In the spring of 1905, Edith purchased a cabin in Albemarle County, Virginia, from an old family friend. The cabin was very rustic and remote, providing just the getaway that Edith wanted. Since it was only about 120 miles from Washington, it offered an easy means of escape for weekends and holidays. They named the cabin Pine Knot, and it became a refuge for the first couple during their years in Washington. Back in the capital, Edith was an unofficial adviser to her husband and was familiar with the political issues he faced. Although she disassociated herself from the President's administration, she placed her office next door to his so that they could confer frequently throughout the day. She also served as a conduit between Roosevelt and a British diplomat who provided the President with information of Russia's activities during the Russo-Japanese War. Edith was a calming influence on her passionate husband, often counseling him to take a more conciliatory tone in his speeches and public statements. She was also considered the better judge of character, and her husband relied on her advice in many areas. Although the role of First Lady was one Edith Kermit Carow Roosevelt neither sought nor relished, it was one in which she remained very active and very popular. Her tenure resulted in the creation of an official staff, and her formal dinners and ceremonial processions served to elevate the position of First Lady. In addition, she preserved for posterity portraits of former First Ladies and their china services, and placed them on display for White House guests. She was noted for her calm composure and high moral standards, and although she was reserved in public, in private she displayed great wit and intelligence. Her accomplishments were not lost on her husband, who praised his wife for combining these talents. Like no other woman, he said, Edith had "the power of being the best of wives and mothers, the wisest manager of the household, and at the same time the ideal great lady and mistress of the White House."