The Harrington Papers are organized into 5 series and span the years 1880-1968. Most interesting is the Correspondence. It appears that John Spaeth, the first unofficial university archivist, grouped Harrington's correspondence (Series I, Box 1, folders 1-7) by topic or subject and wrote brief summaries for each folder. These summaries are included in each folder. Spaeth's organization by folder, along with his summaries have been maintained.

The following descriptions have been taken from Spaeth's summaries: Correspondence for the period November 1907 to March 1908 includes letters from Charles O. Judkins, (Class of 1895; Trustee 1910-1919) F.M. Davenport, and others concerning a proposal that Frederick M. Davenport, Class of 1889, be considered for election to the Wesleyan presidency. (W.A. Shanklin was elected president by the Board on November 13, 1908.)

Correspondence from July 1908 to February 1919 includes an interesting letter by Harrington to the Wesleyan Board of Trustees which is a proposal for the establishment of a woman's college under Wesleyan's auspice. His proposal is acknowledged by J.M. Buckley in a letter of November 20, 1908.

There is correspondence for 1916 with Dr. Olin concerning a new organ for Memorial Chapel.

There is correspondence is with Wesleyan official and contractors and relates to the electrification of the South College chimes in the folder covering the period February 1919 to December 1921.

Correspondence covering the years November 1925 to May 1942 is primarily between Harrington and President McConaughy and concerns such matters as salary, retirement, office accommodations, etc.

Folder 5 correspondence covers the years March 1922 to September 1952. This folder ends with a "Bon Voyage" farewell to Harrington and his wife, Jennie, as they move from Wesleyan to California with their daughter, Mabel Potter (Mrs. George), in 1951. There are long letters by the Harringtons to the Dutchers and Spaeths, also a photocopy of a letter by Dean Acheson.

Correspondence covering the years 1954-1960 includes letters of sympathy to Mrs. Harrington on the death of Karl Harrington. There is some business correspondence relating to the publication of Third Year Latin and other works. Some of the letters are between Mabel Potter and John Spaeth, but also with the publishers.

The last folder of correspondence covers the years 1961-1981 and contain letters between Mabel Potter and Verna and John Spaeth. Topics relates to the re-publication and copyright issues of some of Karl Harrington's writings.

Series II: Writing include some papers presented at the meetings of the Conversational Club and Apostles Club. They also reflect his interests in railroads, Middletown, and Wesleyan history. Harrington's notes and manuscript drafts on Latin are in Series III. His musical interests are reflected in Series IV. Harrington made several attempts at keeping a diary but without much success. Three very incomplete volumes of the diary can be found in Series V. Also in this series is a copy of Harrington's manuscript autobiography.

Series VI consists of 11 volumes of scrapbooks that were kept by Karl Pomeroy Harrington covering the years 1878 through 1936. Volumes are large and very fragile. The scrapbook paper is very deteriorated, pages crumble, items have become loose. The scrapbooks document events at Wesleyan, Middletown, and Harrington's interest in the Methodist Episcopal Church and music. They also contain information relating to other places that Harrington lived or taught, for example, North Carolina.

It should also be noted here that two items were not found when processing the K.P.H. Papers in 2005. The items are: Twentieth Century Club. Annual Report, 1911. Copy of typescript, 5p. and Tibullus Notes IV. These items were present on a preliminary list done in 1984.