Over the past one hundred years, the Library's reading rooms have functioned both as independent entities and as a single administrative unit. Between 1892 and 1915, the public service functions of the Library were part of the Classification and Reference Department. In 1916 the Public Service (Reference) Division was established, uniting the Main Reading Room (MRR), Department of History and Genealogy, E. E. Ayer Collection, and Exhibition Room. By 1920 the Ayer Collection and Wing Foundation were removed from the division and operated independently. From 1920 to 1962 the division's departments included the Rare Book Room, Genealogy, and Reference. A major Library reorganization in 1962 abolished the Division of Public Services, having the reading rooms report directly to the Librarian, later (1965) the Associate Librarian. The Reader Services Department (MRR, Local and Family History, Special Collections, Maps) again formed in 1976, with each section reporting independently to the Director of Library Services. In 1986, the Office of the Reader Services Librarian was created, with the sections reporting to that office.

Includes records of the Reader Services Department, its constituent sections, and predecessor divisions and departments.