The Holy Trinity Library is located in the south east corner of the Undercroft, close to the Poplar Street entrance. In addition to Bibles and books on religious topics there are works of fiction, nonfiction, poetry, music, the arts, and a small audio-visual collection which have been donated by members of Holy Trinity.

The Buchholz Social Justice Collection is in the southeast corner of the library. All books may be checked out by filling out the list on the shelf beneath the glass cabinets. The library is also a cozy space for small group meetings, studying, or just sitting and reading.