The Undergraduate Library traces its roots to 1949 when the University's Galesburg branch closed and its 25,000 volumes were placed in the Library's first floor reading room. Ten years later, the topic of the third President's Faculty Conference was "The Undergraduate Climate at the University", and the outcome of that retreat at Allerton Park was a resolution to construct an undergraduate library. 
On September 21, 1966  that resolution became a reality with the groundbreaking of the new Undergraduate Library, followed by its dedication three years later on November 15, 1969. Built around a 72 by 72 foot square central courtyard, the two-story 98,689 square foot library has a capacity of 150,000 volumes and seats 1,899, with 166 lounge chairs, 542 4x6 foot tables, and 1,191 study carrels. The carrels are 40 inches wide by 30 inches deep, with privacy panels rising to 53 inches above the floor. There are 106 listening carrels offering "106 stations and [with a] control room designed to make available audio materials [the control room provides] channels for 80 monaural or 40 stereo programs, some combination of them at one time, and AM-FM radio". The University anticipated very heavy use of the new facility and so provided twin 26 by 72 foot entrances with circulation desks, allowing books to be checked out in either one. Today only one of the entrances is in use. 
As a rare example of forethought, the building's designers provided "additional telephone and electric conduits 'for eventual use in a computerized on-line circulation system'". Indeed, less than ten years later, in 1978, the Library took "a big step into the electronic age" when "typewriter-size computer terminals [were] placed throughout the Library and in all 35 departmental units". As one alumnus put it, "Gone will be the notched yellow cards [students] had to fill out, one for each book The terminal screen will answer immediately." 
Preliminary site sketches were produced by Ambrose Richardson, Consulting Architect, at the October 26, 1963 Board of Trustees Meeting, "showing how such a building could be constructed below grade in the quadrangle between the Auditorium and the Stock Pavilion and connected with the University Library".  Designed by Richardson, Severns, Scheeler & Associates, Inc, the Undergraduate Library cost $4,240,125, $3,150,000 for the actual construction, $400,000 for furnishings, and $690,125 for landscaping and other miscellaneous costs, leading to a total cost of $42.96 per square foot. The library itself measures 241 feet 9 inches by 217 feet 8 inches, and is connected to the main library through a 170 by 14 foot tunnel. Clark, Altay and Associates designed the interior of the library,  while McCarthy-Hathman Construction Company built the structure.  In 2003, the pedestrian tunnel was redesigned by senior architectural and industrial design students and was painted in a blue/orange gradient, with blue on the undergraduate side gradating to yellow in the middle and finally orange on the main library side. 
The central courtyard of the library is dedicated Edmund Janes James, and the inscriptions around its top are a gift from the class of 1916. The class of 1991 spent $40,000 re-landscaping the courtyard. The large evergreen tree which stands in a concrete pot in isolation on the Undergraduate Library Mall was planted in 1996. 
An often-asked question regarding the Undergraduate Library is why it was built underground. The common answer given by most is that the architects simply didn't want to cast shade on the neighboring Morrow Plots. This is only partially correct. In fact, one of the bigger reasons was that the Campus Master Plan of the day required an open mall behind the Auditorium to maintain symmetry.