Correspondence and other material relating to Ganz's wives, son, and relatives. Ganz is referred to as Rudolph or Rudolf or Rodolphe (with nicknames Rudi/Rudilein/Rudeli/Papi). Parents are Mama and Papa for Rudolf and Sophie Ganz-Bartenfeld. Brothers are Paul, Emil, and Hans. His son (Anton) Roy was born in 1903; letters to him commence from there and return letters are from the 1910s onward.

Early correspondence from Papa is written on the back of J. Ganz (grandfather) business cards. J. Ganz was a photographer. Series includes many picture postcards from Europe and the United States, and some humorous cartoon postcards. Letters from brother Hans Ganz include lots of doodles and fancy calligraphy. There are many letters exchanged between Rudolph Ganz and his first wife Mary Forrest as he was touring as a concert pianist, and the letters include interesting information about each town he visited in the United States and Europe.

Much early correspondence is in German. Other than correspondence, there is a genealogical chart, and small amounts of material about both of Ganz's wives, Mary Forrest Ganz (1867-1956, married 1900-1956) and Esther LaBerge Ganz (1905-2007, married 1959-1972).