The Gregory D'Alessio Papers consists almost entirely of original art, most in black and white (charcoal, ink, etc) but a few in color. The collection includes cartoons, cover illustrations, miscellaneous art, and a small number of subject files.

Cartoons consists primarily of original art, including cartoons drawn for various national magazines, including Collier's, New Yorker, and the New York Times Magazine, as well as contributions to College Humor and one item done for a specific client (Macy's department store). Most are black and white but there are a few color items, particularly the ones done for Collier's.

The bulk of Cartoons consists of original art and proof sheets for the syndicated strip These Women, which D'Alessio drew for more than twenty years. Themes represented in These Women are typical of popular culture's view of women in the 1940s and 1950s: women trying to catch husbands, women spending their husband's money, henpecked husbands, and women in the workplace (usually secretaries). Some of the cartoons from the mid-1940s reflect women working in the aerospace and other industries to support the war effort. Recurring characters include Doris of the Chorus, who collects wealthy suitors and their gifts; Mrs. Brodbeem, an enthusiastic but sometimes silly society woman; Cluny, a teenage girl; Miss Jones, a pretty secretary constantly distracted by her nails and the handsome men who come to see her boss; and The Bride, recently married and adventuring into cooking and other domestic management tasks. A selling point of the strip was that D'Alessio drew many of the characters in the latest fashions. The collection contains both proof sheets with one week's worth, or six panels, to a sheet (some 5600 panels on approximately 930 sheets), and original art for more than a thousand panels. A complete list of all dates represented on the proof sheets is given here. No attempt was made to catalog the dates represented in the original art as the majority of them have partial dates with no year, or no date at all.

The other large subset of Cartoons consists of unidentified or unattributed cartoons (that is, no title and no indication of the client for whom they were done). Of particular interest are the cityscapes or scenes (Oversize 5); a series of one-word or one-phrase cartoons (e.g., an excited family in their new car with the caption "First in the Neighborhood) (Oversize 7); and a five-cartoon set about a family getting their first telephone (Oversize 8).

Covers contains original art for magazine covers for Collier's and Liberty magazines. These are in color.

Miscellaneous art contains an assortment of items including sketches for a few editorial cartoons, a photograph of a painting by D'Alessio (the original resides in the Syracuse University Art Galleries), a set of portraits of wounded soldiers drawn in 1945, and a typescript of a series of limericks with pencil illustrations by D'Alessio. Also in this series are a miscellaneous assortment of original sketches, doodles, and other unfinished pieces, most in black and white but some in color.

A few Subject files complete the collection. These include photocopies of correspondence and of a clipping (about President Truman's having a D'Alessio cartoon on his desk). There is also assorted memorabilia, such as two programs from the Art Students League showing D'Alessio as an instructor, and a few pieces of ephemera illustrated by D'Alessio. There is no original art in this series.