Because of Hank Kaplan's devotion to collecting the stories that often went untold, and his commitment to obscure and ephemeral objects, the scope of the collection is vast. The collection features 2,600 book titles, 500,000 rare prints and negatives, hundreds of linear feet of newspaper clippings from 1890-2007, more than 300 audiotapes and videotapes, over 1200 posters, approximately 200 boxes of publications, dozens of scrapbooks, reams of correspondence, and over 100 boxes of memorabilia items. Examples of memorabilia include autographed money, a heavy bag Cassius Clay punched before renaming himself Muhammad Ali, a gold cigarette case that Max Baer gave his trainer Izzy Kline, and the very scissors that Kaplan used to cut up the hundreds of thousands of newspaper clippings spanning the last century of boxing history.
The bulk of the collection is composed of the newspaper clippings (both from local newspapers as well as boxing periodicals) that Kaplan himself would collect and cut, distributing them into the appropriate files. Often, Kaplan would keep intact a copy of a boxing periodical and use a second copy to clip and interfile into the rest of the collection. Kaplan rarely purchased items for his collection, instead amassing items mostly through donation and trade. Much of the material will make the researcher wonder how Kaplan ever received them. A good example of this is the large amount of plaster mouth casts and rubber mouth guards. There are also items that indicate a close relationship that Kaplan had with others; for example there is a large amount of items belonging to Chris and Angelo Dundee, as well as Kid Gavilan.
The Hank Kaplan Archive is divided into twenty subgroups: Photographs; Artwork; Fighters by Surname; Posters;Bouts; Audio/Visual Material; Fighters by Weight Class; Boxing Personalities; Jewish Fighters;Scrapbooks; Memorabilia, Souvenirs, and Ephemera; Publications; Programs, Press Kits and Handbills;Locations; Fistic Arcana; Autographs; Hank Kaplan; Angelo Dundee; Muhammad Ali; and Organizations. See Collection Arrangement for more detailed information.