The James H. Dilonardo Collection documents aviation and aviators, predominantly of the Pacific Northwest in the middle of the 20th century with photographs, slides, clippings, printed ephemera, notes, audio recordings and film.

The collection is largely made up of visual materials, with 1,130 photographic prints and 40 slides. The prints are primarily black-and-white and the slides are all color. The photos document aviation in general and include numerous types of aircraft, both domestic and foreign as well as many aircraft from the World War I and World War II eras. Boeing aircraft and people associated Boeing Field and aviation in Seattle, Washington, including female aviators, are well represented.

The textual materials include both collected and personal documents. An invoice ledger for Boeing Field include several pages of historical notes by Dilonardo and a "Repair Station Manual" from about 1958 includes many personal notations by Dilonardo. Other textual items include ephemera related to World War II, United Airlines, and assorted subjects.

The audio-visual series also includes a mix of personal items and collected materials. The sound recordings predominantly consist of informal interviews conducted with members of the OX-5 Aviation Pioneers of the Pacific Northwest. Film footage appears to be a mix of collected and private films but have not been viewed by archives staff.