The papers of Elizabeth Severn (1879-1959) and Margaret Severn (1901-1997) span the years 1880-1994, with the bulk of the material dating from 1910 to 1992. The collection is in two parts. The part processed in 2013 is focused on Elizabeth Severn's activities as a psychotherapist. The 2018 addition consists primarily of material related to dancer Margaret Severn, Elizabeth Severn's daughter. The collection contains correspondence, writings, photographs, printed matter, sketches, and digital files consisting of two video documentaries, edited correspondence, and draft writings. The digital files are related to Margaret Severn.

In the first part of the collection, focused on Elizabeth Severn, the correspondence is almost entirely incoming letters, mostly from patients of Severn. There are also some carbon copy letters written by World War II American Field Service volunteers giving descriptions of wartime activities and postwar Germany. Other correspondents include William Beebe and H. Halliday Sparling. Also of interest are the notes made during lectures and seminars by Paul Federn and Robert Waelder. Although Elizabeth Severn and her daughter Margaret maintained a long correspondence, Elizabeth Severn's portion is not represented. Margaret, reportedly, in accordance with her mother's wishes, burned her mother's letters in 1986. Elizabeth Severn's speeches and writings files include drafts of three unpublished books as well as a set of typescript essays and speeches. The printed matter includes publicity material for Elizabeth Severn's psychotherapist career. The leaflets and cards advertise her lectures or her availability for therapy sessions and document her travels. Newspaper clippings concern Severn lecture appearances, news about psychoanalysis, and clippings of people who were close acquaintances or patients of Severn. Reference copies of some photographs transferred to the Prints and Photographs Division, including those with substantial writing on the back, have been kept with the papers. Photographs include travel pictures, snapshots, and portraits of Elizabeth Severn, as well as photographs of friends, family, and patients, including a group of photographs of Severn with her analyst Sándor Ferenczi and his wife, Gizella Ferenczi.

The 2018 addition is substantially larger than the original collection. Material concerning Elizabeth Severn in the addition includes addressed envelopes tracking her travels and residency changes from 1907 to 1935, received correspondence, writings, and miscellaneous documents and printed matter. The bulk of the 2018 addition consists of family correspondence: Margaret Severn's letters to her mother and grandmother (Amma). In her responses to her mother's letters, information can be gleaned about Elizabeth Severn's activities, travels, opinions, and her ongoing psychoanalytic relationship with Sándor Ferenczi.

Margaret's letters to her mother and grandmother provide a detailed description of her dance career and her personal life from 1919 to 1939. She often wrote daily letters and was surprisingly frank with her mother concerning all aspects of her life including sexual activity. Margaret Severn performed at the highest professional level of the dance world in the United States and Europe. Trained as a ballet dancer when there were no ballet companies in the United States, she spent years performing in vaudeville, cabarets, and in the New York theater. In 1932 she moved to Paris and danced ballet in a professional world dominated by Russian émigrés. Over the years, she danced with many of the top dancers and choreographers of her time, and her letters provide an inside view of the world of dance from 1920 to 1939. Dancers, choreographers, musicians, and impresarios who worked with Margaret Severn, often appearing multiple times over the years, and who figure in her letters are many but include the following: Luigi Albertieri, Agnes De Mille, Michel Fokine, Ota Gygi, Eugene Iskoldoff, Kurt Jooss, Bronislava Nijinska, Ida Rubinstein, Ruth St. Denis, and Alexander Steinert. An abortion in April 1925, fully described in the letters, was the result of her 1924-1925 affair with Hungarian violinist and fellow vaudeville performer, Ota Gygi.

Margaret Severn had her first major critical acclaim in 1920 when she performed in the Greenwich Village Follies using masks created by artist Wladyslaw T. Benda. After the success this performance, Benda taught Severn how to make her own masks for dance performances. Her mask dances remained a signature performance piece throughout her dance career. Two small masks of Margaret Severn are in the collection. In addition to an active performance schedule, Severn opened the Dancers' Club at 347 W. 56th Street in Manhattan (1930-1932). The club provided living accommodations, mail and laundry services, practice facilities, an employment register, and social activities for professional dancers, teachers, and students. Margaret sometimes included newsletters from the club with her correspondence to her mother. In 1932, Margaret traveled to Budapest to visit her mother and subsequently settled in Paris. She danced with Bronislava Nijinska's ballet company in 1932 and with Ida Rubinstein's company for the 1934 Paris Opera House production that included the premiere of Stravinsky's Perséphone . Her letters to her mother provide lively backstage descriptions of rehearsals and performances. Margaret Severn performed as principal dancer and ballet master for a traveling company called the Ballet Russes de Paris, 1935-1937. The company participated, with Margaret Severn as lead dancer, in the July 1936 outdoor spectacle in Nymphenburg Park, Munich, Germany, called "Nacht der Amazonen" (Night of the Amazons). For the performance, Severn was kidnapped by horseback-riding Cossacks and later saved by Amazons (played by German women) on horseback. "Nacht der Amazonen" was an annual event, 1936-1939.

The letters have many editorial marks, usually in green ink, that were made years later when Margaret Severn was working on her memoir. Envelopes have been inscribed with notes about the contents of the letter. The original writing in the letters and on the envelopes, however, is still legible even with the edits. Although she never completed her memoir, she did publish three articles in Dance Chronicle based on parts of her correspondence. The articles are in the autobiographical writings file. The digital files include her draft memoir and typed and edited transcriptions of many of the letters, including early letters for which the original paper copy is not in the collection. Presumably, the transcriptions of these early letters are edited versions. Margaret Severn was also an artist. In addition to a folder of her sketches, many of her letters are illustrated.

Peter Lipski's two film documentaries on Margaret Severn, Dance Masks: The World of Margaret Severn (1980) and Portrait of an Artist as a Young Woman (1992) are both available as digital files.