The largest in the collection, the Correspondence series includes the general correspondence of Jacques Seligmann & Co., Inc., with individuals and museums; the personal business correspondence of Germain Seligman; legal correspondence and other documentation concerning specific and general legal affairs; abstracts of letters sent; a small group of outgoing correspondence; correspondence of staff and agents Theresa D. Parker, Clyfford Trevor, and Rolf Hans Waegen; and inter-office memoranda.

The entire history of the firm, especially the years when the New York office functioned as the primary headquarters of the company, is well documented in this extensive series. The bulk of the correspondence reflects the period when Germain Seligman directed the firm and the New York office, although there is a small series of Paris office and gallery correspondence written mostly by Jacques Seligmann. Researchers will find correspondence with both U.S. and European clients, collectors, museums, dealers, galleries, shippers, U.S. and foreign government agents, bankers, and insurance firms in the General Correspondence (Series 1.3) and Museum Correspondence (Series 1.4). For additional documentation of the firm's business affairs, researchers should also consult Germain Seligman's Correspondence (Series 1.5), which includes not only personal invitations and announcements but also business correspondence that he considered to be of a more private nature. Legal Correspondence Files (Series 1.6) is arranged in a separate subseries and houses several interesting files concerning general legal affairs, specific lawsuits, and attempts to recover Seligmann family and gallery artwork stolen in Paris during World War II. Also of notable interest is the subseries housing the Inter-Office Memoranda (Series 1.13), which includes notations made by Germain Seligman and staff about clients, collectors, possible sales and acquisitions, and many other business matters. The interesting commentary was clearly intended to be read by staff only.

The Correspondence series is organized into the following subseries. More detailed descriptions for each of the subseries follow, with a corresponding box and folder inventory. The bulk of this series has been scanned. Details of exceptions are provided in the arrangement notes for each subseries.