The Tredyffrin Library, with 18,000 square feet (1,700 m2) of space as of 1977, is located in Strafford. The architectural firm Mitchell/Giurgola developed the Tredyffrin Library. It has an amphitheater that is focused on a park in a southward direction. The library has a single large reading room. The library building has a larger two story end, while the other end has only one story at the upper level. The facility has toilets, workrooms, and offices at the main level are in a separate element of the structure from the main reading room, and this structure juts out from the flue. Architectural Record said that this "allows direct access to the reading room from the public entrance."
Architectural Record stated that Tredyffrin Library and the library built in Condon Hall of the University of Washington School of Law, which was also designed by Mitchell/Giurgola, have common underlying concepts. According to the publication, the shared concepts were "unusual sensitivity in using natural light to best advantage while warding off the sun," a "quickly apparent organization of functions," and being "responsive to the varying situations in which it is built."