This series includes letters written and sent to Roscoe Cather by Willa Cather. Cather would occasionally address a letter to both Roscoe and his wife, Meta, or to Roscoe and their sister Elsie. Also included in this series are two letters sent to Roscoe and Willa's brother Douglass, one being addressed to both Roscoe and Douglass. Cather often forwarded letters she received to Roscoe, including a telegram from Carrie Miner Sherwood and a single letter from Isabelle McClung Hambourg in which Hambourg writes to Cather as "Dearest Molly." Additional letters or notes are sent to Roscoe by Cather's secretary Sarah J. Bloom. These letters are distinct from those on which Bloom signed Cather's name upon her request.

This series includes letters sent to Meta Cather, the majority of which are from Willa Cather. There are also letters written to Meta from Elsie Cather and Edith Lewis. Enclosed in a 1947 letter sent to Meta from Edith Lewis are four letters that Roscoe wrote to Cather. Lewis wished Meta to have the letters after Roscoe's death. There are numerous letters from Cather's sister Elsie Cather, who wrote to Meta just four days before her own death in 1964. Elsie Cather enclosed several family stories in letters sent to Meta in 1961.

This series includes letters written by Cather to her nieces Virginia, Margaret, and Elizabeth Cather. Cather sent letters to the individual girls or would send them to all three together. She sent numerous letters to Margaret and Elizabeth, the twins, endeared to her as the "twinnies". There are several letters from Edith Lewis to the Cather girls. Virginia Cather married John Hadley Brockway, who served in the U.S. Navy. Margaret Cather married Richard Shannon in September 1938. After her marriage, letters were sent to her as "Mrs. Richard Shannon". Elizabeth married Lynn S. Ickis in April 1938, and her later letters are addressed to "Mrs. Lynn Ickis". Margaret and Elizabeth visited their Aunt Willa on the island of Grand Manan in Canada, in 1936 and 1937, staying for a month each summer. This experience is related in an essay titled "Memories of Aunt Willa Cather," written by Margaret Cather Shannon. One letter, dated 1936, was written to them by their father Roscoe. There are several letters from their aunt, Elsie Cather, who made her home in Lincoln, Nebraska, and taught at Lincoln High School. Letters sent in 1962 include those Meta Cather wrote to her daughter Virginia about a commemorative bust of Willa Cather placed in the Nebraska State Capitol.

Cather received letters from her brother Roscoe, which are a part of this series. One folder of letters were designated as "family letters" by Margaret Cather Shannon and these have been left together. There are also several letters from Alfred A. Knopf. Two letters reference the question of whether to produce Armed Services Editions of Cather's books Death Comes to the Archbishop and My Ántonia.

Cather wrote letters to her mother, Mary Virginia "Jennie" Boak Cather, in which she discusses health issues, both her mother's and her own, housekeeping activities, and clothing. Cather talks of peace in a letter dated 11 November 1918, the day World War I ended and Germany signed an armistice agreement. The majority of letters reference the activities of family members, particularly Cather's siblings and their children, and other people that were close to the Cather family.

This series includes correspondence sent to Elsie Cather from Cather, though the majority is from her brother Roscoe. Many of the letters discuss financial issues and Roscoe shares news about his daughters and their children. This series includes several newspaper clippings of Elsie Cather's obituary.

This is a small set of correspondence sent by Cather to non-family members, including letters to Miss J. Speiser of LIFE magazine, one is addressed to "My darling May," and a letter exchanged between F.P. Keppel and Alfred A. Knopf asking Cather to attend a meeting at the League of Nations.

This series includes photographs of Roscoe and Meta Cather, their daughters Virginia, Margaret, and Elizabeth, and photographs of Willa Cather with the family. Also included are articles by and about Cather, unedited galley proofs for Neighbor Rosicky, memoirs about Cather, items such as bank receipts, baptismal and marriage certificates, and family history.