HCLA's holdings on the labor movement trace the continuous effort by working men and women to win dignity and prosperity. Records of unions include minute books, executive board documents, and office files for important organizations, including the Amalgamated Association of Iron, Steel, and Tin Workers, Pennsylvania Federation of Labor, Pennsylvania AFL-CIO, United Steelworkers of America, Amalgamated Lithographers of America, and the International Photoengravers Union. There are also collections of records for many local unions and central labor bodies in Pennsylvania.

HCLA has personal papers for several notable labor leaders from the United Steelworkers and United Mine Workers, including Philip Murray, David J. McDonald, I. W. Abel, Clinton S. Golden, and William Mitch. Letters, diaries, reports, and photographs from several union organizers and staff members are included in the labor materials.

Note: Pre-approval is required for access to some labor materials. Consult the head of the HCLA, Jim Quigel, for more information.