One of the most-visited rooms in the Cathedral is the Library, located at the extreme left of the building as you enter from Avenue E. Although there is no full-time Librarian, this Library is open to the public for research and casual reading.

The San Antonio Scottish Rite Library has a limited collection of books dedicated to many subjects including Texas, world and military history. Most importantly, the Library has an extensive collection of books related to Freemasonry. Here, the Masonic researcher can find volumes dedicated to almost every aspect of the Craft, from the York Rite to the Scottish Rite to the Shrine, from Blue Lodges to Prince Hall Masonry, from youth groups to invitational bodies.

Through magazines, pamphlets, single-volume books, and multi-volume encyclopedias, both the dedicated Mason and the curious non-Mason can find answers to their Masonic questions in the Library. Complete collections of proceedings from the several Grand Masonic Bodies make the Library of interest to genealogists and Masonic historians as well. A few extremely rare and aged Masonic volumes are available for perusal by appointment only.

The furnishings of the library provide a quiet and appropriate atmosphere for both casual reading or study and research. Besides the beautifully decorated ceiling and small displays related to San Antonio Masonic history, of particular interest are the carved wooden eagles which rest above the doorways leading into the Library.