Access Services (5th floor) - The Access Services Department manages Circulation and Interlibrary Loan services. The Circulation staff assist patrons by checking materials in and out of the library, searching for holdings, maintaining the reserve collection, ensuring that library materials are shelved in proper order, and answering basic questions about the library. At the request of VMI cadets and faculty, Interlibrary Loan staff borrow research materials not owned by Preston Library from other libraries in Virginia and the United States.

Government Publications (650 level) - Preston Library maintains a selective federal depository of government publications.  Designated in 1874, the depository collection includes materials from the departments of Commerce, Defense, Interior, Labor, State, and others.  Questions regarding government information are handled by the depository librarian during reference hours.

Media Services (4th floor) - The Media Services Department provides services dealing with audio/visual materials, including reserving AV materials for rental or purchase, loaning AV equipment for classroom use, videotaping, editing, photography, duplication of video and audio tapes for academic use, dry-mounting and laminating, and reference guidance for AV software and equipment rentals and purchases. Service requests must be made with as much advance notice as possible.

Reference (5th floor) - The Reference Department coordinates library instruction, works with library patrons conducting research, and is available to answer more detailed research and general interest questions. Members of this department work with instructors to coordinate the use of library resources and with students on research projects.

Technical Services (4th floor) - The Technical Services Department manages the acquisition and cataloging of library materials.

VMI Archives (4th floor) - The Archives manages the Institute's historic official records, manuscripts, photographs, and 19th-century alumni biographical and genealogical information. Rare books and other rare materials are located in the VMI Archives.