- Level 5: Books QD - Z, Periodicals, Microform, Study Rooms, Curriculum & Children's Books, Scanner, Tables.
- Level 4: Books G - QC, Silent Study Area (with Tables and Study Carrels)
- Level 3: Entrance, Public Service Desk (Reference & Circulation), Café TJ, Research Commons/Computer Lab, Copier & Scanner, Instruction Room (Room 315), Tables
- Level 2: St. Louis Mercantile Library, COM2, Government Documents, Folio and Oversize Books, Tables, State Historical Society of Missouri Research Center - St. Louis
- Level 1: Books A - F, Additional Mercantile exhibits, Study Carrels and Tables
Restrooms:
- On Level 3 (Main floor):
- The Women's restroom is located down the hall past the Public Service Desk.
- The Men's Room is located down the hall past Café TJ.
- On Levels 4 and 5, restrooms are located along the front (south) wall of the library.
- See the floor plans for restroom locations on Levels 1 and 2 .
- Restrooms on Levels 1 and 3 are wheelchair accessible.
The St. Louis Mercantile Library is located on Level 1 and Level 2 of the Thomas Jefferson Library. The University Archives are also currently handled by the Mercantile Library staff.
The State Historical Society of Missouri - Saint Louis Research Center is located on Level 2 of the Thomas Jefferson Library.
Note: The Ward E. Barnes Library was merged into the Thomas Jefferson Library in May 2014.