The Tamiment Library and Robert F. Wagner Labor Archives Printed Ephemera Collection on the United Hatters, Cap, and Millinery Workers International Union largely consists of agreements and contracts, it also contains constitutions and reports as well as printed ephemera such as fliers, circular letters, newspaper clippings, programs, pamphlets and other publications.

Series I: Agreements and Contracts, 1940-1989, consists of legal size agreements and contracts with companies around the United States and Canada.

Series II: General Files, 1920-1978, contains material from the United Hatters, Cap, and Millinery Workers International Union, however, this series also contains material from the Cloth Hat, Cap, and Millinery Workers International Union and the United Hatters of North America, two predecessor unions. The General Files consist of constitutions and financial reports as well as publications put out by the National Recovery Administration on codes of fair conduct for the hat manufacturing industry. There are fliers from the Millinery and Hatters Committee for Wallace, documenting the committee's support of Henry A. Wallace's bids for the US presidency in 1944 and 1948. The collection also contains a small number of fliers and ephemera regarding the Union Label Campaign and various union and national elections. In addition to material from the international and national bodies of the United Hatters, Cap, and Millinery Workers International Union, there are also files from locals, including Locals 3 and 8, both from New York City. The file on Local 8 contains financial reports, local election fliers, rank and file produced circular letters, and a constitution dated 1922, at that time under the auspices of the United Hatters of North America.