Library 72dpi 860wMany of Whitehall's first-floor rooms were decorated to have a distinct masculine or feminine feel, according to who principally used the room. The Library, used by Flagler as a reception area to greet guests and meet with business associates, was decorated in the masculine style of the Italian Renaissance.

Artisans molded and painted the Library's cast plaster and fabric ceiling to look like wooden beams with leather insets. This practice was one of many examples of modern craftsmanship and technology which helped craftsmen complete Whitehall in only eighteen months.

Flagler family portraits are mounted on the Library walls, including a painting of Henry Flagler above the fireplace. Also hanging on the walls are portraits of Flagler's father, Reverend Isaac Flagler, daughter, Jennie Louise Flagler Benedict, and first wife, Mary Harkness Flagler.

The Great Florida Marsh by Martin Johnson Heade, hangs on the North wall. Heade was an American landscape and floral painter who worked in St. Augustine under Flagler’s patronage. Other notable works of art include a bust of George Washington, whom Gilded Age Americans admired as a great American hero and two busts of Roman senators.