Although the Reference Services Section was not officially organized until 1983, reference services have been provided to the Library's readership since 1893. During the Library's first years, reference services were handled by the Classification and Reference Department, by personnel staffing the departmental reading rooms, and by the Librarian. In 1915 a Reference Division was created (name changed in 1916 to Public Services Division). Reference remained a part of Public Services until that department was disbanded in 1962. An independent Reference Department was itself eliminated two years later (1964), and until 1966, only a reference librarian position existed. In 1966, a new Reference Department was created; by 1970 this department had been absorbed in a new Public Services Department (Reader Services by 1974). After several years in which reference was a part of the Main Reading Room Section, a separate Reference Services Section of Reader Services was created in 1983.

Includes reference correspondence and daily logs of subjects studied at the Library.