Professional papers include correspondence with Karl M. Dallenbach, Edwin G. Boring, and other participants from the Inter-Society Color Council concerning his research in vision, particularly color vision, night vision, visual acuity, and color aptitude testing; newsletters, color swatches, and testing materials concerning his work (1940+) with Carl Foss and other members of the Inter-Society Color Council on the development of the Color Aptitude Test (CAT), a project sponsored by the Federation of Societies for Paint Technology; correspondence, minutes and pamphlets, 1955-1967, concerning the work that Dimmick, Foss, and Deane B. Judd did as members of the Committee on Uniform Color Scales of the Optical Society of America and for the National Bureau of Standards; correspondence, notes, and reports, 1964-1967, concerning his retirement activities as a consultant for the Biological Science Communications Project; papers concerning Dimmick's color specifications research based on "Just Noticeable Differences of Hue;" papers concerning his biographical research on his former professor, Edward Bradford Titchener; letters from Titchener to Dimmick and Mrs. Dimmick; recorded interview with Harry P. Weld, a Titchener colleague, and genealogical tables of the Titchener family. Personal papers include family letters; photographs; and other material belonging to Dimmick or his wife, Claire Comstock Dimmick.