The Brooklyn Historical Society ephemera collection is an artificial collection compiled by Brooklyn Historical Society staff, that continues to be updated to the present day. The collection contains pamphlets, cards, advertisements, newspaper articles, magazines, and more, dating from 1770 to the present documenting Brooklyn, New York City, and Long Island.

Business related materials in this collection include items such as checks, receipts, business and trade cards, bank notes, bank statements of condition, and promotional announcements and brochures. Religious materials include issues of the periodical The Parish News, dating between 1905 and 1906, as well as items pertaining to various Brooklyn churches that existed during the early 19th century, such as the Brooklyn Tabernacle, First Presbyterian Church, Saint Barnabas Church, and Saint Michael's Church of Bay Ridge. Tickets, pamphlets, service programs, announcements, miscellaneous flyers, newspaper clippings, and obituaries can be found here

A variety of materials documents civil organizations, including newsletters, special announcements, and invitations. Invitations to Fire Department balls and galas can be found, some dating to the 1840s. The Parks folder contains materials relating to Prospect Park, ceremonial dedications, annual reports, tour programs, and invitations. Also included are materials related to specific celebrations such as the Hudson-Fulton celebration of 1909, the Williamsburg Bridge opening of 1903, the Long Island Tercentenary Banquet of 1936, the George Washington Centennial celebration of 1889, and the Bicentennial of 1975 to 1977. Brooklyn clubs materials include theater programs, event, menu, and announcement information. Pamphlets, seating lists, donor lists, bulletins, handbooks, and correspondence, all relating to theater programs.

The majority of materials pertaining to entertainment is theater programs, as well as event programs and announcement materials. Theaters are listed alphabetically, and include The Athenaeum, Brooklyn Academy of Music, The Majestic, Montauk Theater, New Brighton Theater, and Payton's Theater, as well as various theaters not documented extensively enough to occupy individual folders, such as the Germania Theater, Brooklyn College Theater, Prospect Hall, and the Carnegie Theater. Each folder contains items such as programs, booklets, and tickets. The collection also includes musical compositions, Coney Island memorabilia, opera programs, and playbills. Materials include event calendars, promotions, programs, annual schedules, newspaper clippings, posters, flyers, brochures, and sales guides. Sports events are documented through miscellaneous tickets and newspaper clippings. It also contains programs and schedules from the Crescent Football Club (1891-1892), the Brooklyn Prep Midgets' football team (1922), the Brooklyn-Queens Marathon and Indoor Games (1926), the Brooklyn Dodgers Football team (1940), and the Brooklyn Cyclones minor league baseball team (2001).

Materials related to the military pertains to the 23rd Regiment, the Navy and the Brooklyn Navy Yard, memorial services, Memorial Day celebrations, Ulysses S. Grant, and miscellaneous notices, a 1918 World War I Christmas postcard, invitations, and announcements. Included are identification cards, like Frances Haber's Brooklyn Navy Yard I.D. dating from 1943. Other items of interest include tickets and invitations for veterans' events and celebrations.

Transportation is represented through identification cards, tickets, booklets and more, pertaining to trains, underground and elevated subways, highways, ferries and bridges.