The Theron W. Kilmer Portrait Photograph Collection spans the period from ca. 1920 to ca. 1942, and primarily contains silver gelatin and a few gum bichromate photographs of men. About half of the 66 portraits depict physicians, clergymen, and other men identified by name. The remaining portraits are studies of African-American men, men with beards, and such ethnic character types as "The Sheik" and "The Hindu." Most of the prints are signed and bear stickers from camera club exhibitions throughout the United States.

Kilmer's writings on photography provide a window into his techniques, as well as his personal aesthetic. In the American Annual of Photography (1942) he explained that he enjoyed seeing the faces of his colleagues on his study walls. He also wrote there that he photographed men because "Women usually want all the "lines taken out" - leaving the face a smooth globe, devoid of all character." Kilmer was particularly interested in facial lines as evidence of expression and character.

Photographs are arranged alphabetically by surname, with unidentified sitters filed at the end. In some cases, further information about the sitters has been included in the box and folder listing.