The Newberry Library was incorporated as a free public library in the State of Illinois, April 13, 1892, and Bylaws governing the new corporation were adopted by the Board of Trustees on June 14, 1892. A Certificate of Amendment to the original Articles of Incorporation, enlarging the Board of Trustees from thirteen to a maximum of twenty five, was approved Dec. 8, 1972. Bylaws revisions over the years have formalized the Trustees' diminished role in the day to day operations of the Library.

Series includes the Certificate of Incorporation, 1892, the Certificate of Amendment, 1972, Bylaws, 1892-1988, the April 25, 1892 deed transferring property from the Newberry Estate to the Library, and schedules of the Library's personal and real property as of Apr. 25, 1892. The printed 1892 "Certificate of Incorporation and Incorporation Act" contains copies of Walter L. Newberry's will and the 1891 law, "An Act to Encourage and Promote the Establishment of Free Public Libraries in Cities, Villages and Towns of this State."