Contains notes, reports, and other materials related to Gates' work with the Department of Middle American Research at Tulane University. Includes information on the history and archaeology of Guatemala, as well as to the contemporary situation in the region. Most prevalent are documents relating to Tulane's 1925 agricultural survey of the Southern Mexican state of Tabasco. Materials date from between approximately 1920 and 1926.

Contains the San Diego Museum's articles of incorporation, a multiple page, typed membership list, five bulletins/announcements from 1917 to 1930, an announcement appealing for members of the museum, and Gates' life membership card for the museum.

Contains administrative notes relating to the Aryan Theosophical Society branch in Point Loma, California, as well as one set of notes on the Society's study of Isis Unveiled. Gates' involvement with the Aryan Theosophical Society lasted from the 1905 until the years following the First World War.