The Lower School librarian organizes classes once a week for boys in each grade. The librarian encourages boys to read a wide range of books and promotes the life-long habit of reading for recreation and information gathering. Lessons taught provide the necessary skills for independent use of libraries. Students in all grade levels are trained to search the online electronic catalog (LIONS: Library Information Online System) for library materials.

With students in the first grade, the librarian shares literature related to various subjects taught in the classroom. These titles include classics, folklore, current publications, and Caldecott winners. The students also learn the difference between fiction and nonfiction books and how to locate these books in the library. The second graders learn the arrangement of nonfiction books, review the use of the electronic catalog, and learn to use reference sources online. In the third grade, the boys continue to hone their research skills using the online catalog and online subscription services available to the St. Mark's community. They are introduced to the Reference section of the library and learn about the types of and uses for such information. The third and fourth graders participate in the state-wide Texas Bluebonnet Award program. The fourth grade uses the library throughout the year to work on research projects related to the Humanities and Science curriculum. They use previously learned skills to find information in both print and electronic resources.

During each grade level's weekly library time, all students may check out library books to take home. The library is also available to students during the day and before and after school for research and/or book checkout. Parents are encouraged to check out additional books for their children at any time.