The records of the early hatters unions concentrate on the International Trade Association of Hat Finishers of America, and include the union's convention minutes, officers' reports (which include financial and membership records), and scattered presidential reports on major problems confronting union. (See Series IX: Scrapbooks for the Hat Finishers of North America Executive Board minutes.) There are also minute books for three locals: Brooklyn (1868-1893), Boston (1868-1882), and Newark (1853 1870), as well as list of apprentices in Bethel, Conn. (1860-1892). Other affiliated groups represented by various documents here are: Silk Hat and Fur Finishers' Union, Hat Makers National Union, Wool Hat Finishers Convention proceedings, and the Convention of Hatters to fight convict labor proceedings.

The extensive records of the United Hatters of North America include: convention proceedings, several constitutions of UHNA and locals, financial records (including some strike benefit records), records of union labels issued to employers, records taken from individual applications, and miscellaneous files on such issues as communist activities within the union and relations between United Hatters and Cloth Hatters.

The Cloth Hat, Cap and Millinery Workers International Union national office records include National Executive Board minutes, general Executive Board minutes, and correspondence on jurisdiction. Other files relate the union's stormy relationship with the International Workers of the World, and contain scrapbooks and pamphlets on factional, jurisdictional and racketeering issues. There is also a typescript of a biography of Max Zuckerman. Some of the correspondence here and in the United Hatters section also relates to jurisdictional disputes between the United Hatters and the Cloth flatters, and the latter and the American Federation of Labor. The disputes between the United Hatters and the Cloth Hatters were resolved through amalgamation following a series of conventions in 1933-1934, the records of which comprise one section of this collection. Two additional boxes contain the financial records of the Joint Union Label Board, a cooperative endeavor of the United Hatters and Cloth Hatters.

The large body of material on the Danbury Hatters' Case (Loewe v. Lawlor), in which the Supreme Court first declared secondary boycotts illegal, includes: court transcripts, records of negotiations between the unions and the hat manufacturers, local newspaper clippings, government and employer comment, and records of strike benefits, local unions, and the property holdings of the hatters attached by the court. There are also court transcripts of related cases involving hatters. After 1934 the United Hat, Cap, and Millinery Workers International Union (UHCMW) was the only hatters union in the U.S. Documents found here on the UHCMW include records of union labels issues, and arbitratration proceedings, as well as some records and proceedings relating to the millinery industry codes of the National Recovery Administration under the New Deal. There are also several pamphlets and reports, including "Business Mortality of the Millinery Industry" (1942) by Edward Wagenfeld.

This collection also includes material assembled by Charles H. Green for his 1944 authorized history of hatters' unionism, The Headgear Workers. Of particular interest is material not included in his study that covers technological developments in the industry, its economic history, and trade associations. Addresses and brief histories of the union by union officials, Max Zaritsky and others, are included. There are also documents relating to the conduct of locals, apprenticeship indentures, mortuary benefits, and a handwritten constitution, dated 1827, of a Cincinnati hatters local.

Approximately fifty photographs and seventeen scrapbooks are included in the collection. The first scrapbook contains International Association of Hat Finishers of North America minutes (1836-1893). The rest contain United Hatters of North America materials, including twelve membership books for the various trades, two petty cash registers, a strike benefits book, and a World War I clippings scrapbook.