Contains an address and memo book, diaries, and financial records, dated 1917 to 1942.

Family members have a memory of Mahonri jotting down thoughts and arranging and rearranging earlier notes for the purpose of writing his life story. Mahonri’s material is arranged in alphabetical order with titles as he named the subjects. Material is undated.

Contains materials and documents relating to Mahonri Mackintosh Young's preparations to write an autobiography. Undated.

Contains photocopied art and sketchbooks, and notes and other ephemera relating to the work of Mahonri Mackintosh Young for various purposes in various places. Materials date from 1870 to 1956.

Newspaper clippings on Mahonri Mackintosh Young's life and carreer, dated 1898 to 1957.

Contains drafts, certificates, and other writings, dated 1907 to 1955.

Reference files on people collected by Mahonri Mackintosh Young containing images and articles on a wide variety of persons and subjects, including artists, authors, journalists, illustrators, cartoonists, sculptors, architects, and politicians, and on other topics. The folders in this series are identified by name rather than by folder number. Undated.

Scrapbooks contain images and articles collected by Mahonri Mackintosh Young on a wide variety of persons and subjects, including artists, authors, journalists, illustrators, cartoonists, sculptors, architects, politicians, and miscellaneous. Undated.

Subject reference files collected by Mahonri Mackintosh Young, undated.

Contains Mahonri Mackintosh Young's research files on various artists and subjects, as well as audubon plates and their reprints, undated.