The Brewster Family Papers are comprised primarily of the papers of Anna Gertrude Brewster and Mary Kate Brewster, dating from 1882 to 1967. The collection includes biographical material, family photographs, diaries, scrapbooks and other memorabilia, correspondence, writings, and the Brewster children's family newspaper (1884-1885). Mary Kate's papers include records of her two trips around the world (1893-1894 and 1896-1897), typescripts of novels and plays, correspondence with family members as well as with actors and actresses of the day, and her newspaper articles and theatre reviews. Anna Gertrude's papers include personal diaries and family correspondence, as well as letters received from former students. Both sisters kept annual records of finances, books read, and letters written and received. In addition, Anna Gertrude generally kept a record of social calls received and returned in a given year. These notations are located at the back of the diaries.

This collection is organized into four series:

• I. General Family Information
• II. Mary Kate Brewster
• III. Anna Gertrude Brewster
• IV. Other Family Members

Series I includes general family information, articles about the Brewsters, photographs, and the children's newspaper. It is followed by Series II and III, the papers of Mary Kate Brewster and Anna Gertrude Brewster, respectively. In both series, diaries are arranged chronologically. Correspondence is divided into two sub-categories, family and other. Letters to and from Mary Kate during her two trips to Australia are filed separately. Writings are arranged by type and then listed alphabetically by title. Personal memorabilia appear at the end of each series. Series IV consists of correspondence and memorabilia of other family members.