The "Downstairs Office Files" represent the core of Dichter's correspondence as it was moved from the Castle to the downstairs office in his last home at Cortlandt Manor. While the span date of the files runs from a 1937 letter from the Viennese psychoanalyst Dr. Wilhelm Stekel (1868-1940) all the way to 1989, the vast majority date between 1972 and 1985, the period in which Dr. Dichter had repurchased his business from Lehigh Valley Industries, Inc., and still retained a large number of American and foreign clients. Regrettably, the presumably equally large volume of Dichter's pre-1972 correspondence has been lost.

As noted, the largest part of this correspondence deals with Dichter's clients, that is, it supports the research proposals and studies. There are also a much smaller number of topical files of materials collected by Dichter on such subjects as Watergate and cultural bellwethers like the Bhagwan Shree Rajneesh, plus "fan mail" from a wide range of former students and admirers. The files also document Dr. Dichter's role as a teacher of marketing at Mercy College and Nova University, including course outlines and copies of some students' seminar papers, and his relationship with Herman Kahn and the Hudson Institute. Lastly, the files contain some limited information on Dichter's participation in local community affairs.