The papers of Princess Marie Bonaparte (1882-1962) span the years 1889-1962, with the bulk of the material dating from 1913 to 1961. The collection documents Bonaparte's interest and involvement in the field of psychoanalysis. The papers are in French, German, and English and include journals, memoirs, correspondence, drafts of writings, notebooks, legal documents, obituaries, genealogical notes, photographs, watercolor drawings, and printed matter arranged in five series: General Correspondence, Subject File, Writings, an Addition, and Formerly Closed material.

The General Correspondence series consists of letters to Bonaparte by fellow psychoanalysts including Edward Bibring, Grete L. Bibring, Ruth Mack Brunswick, Max Eitingon, Paul Federn, Sándor Ferenczi, Anna Freud, Dora Hartmann, Heinz Hartmann, Ernest Jones, Hans Lampl, Jeanne Lampl-de Groot, Rudolph Maurice Loewenstein, Heinrich Meng, Géza Róheim, Hanns Sachs, and Max Schur. Relatively few of Bonaparte's outgoing letters are included in the series other than numerous letters written by her to Eitingon between 1925 and 1941.

The General Correspondence series traces Bonaparte's introduction to psychoanalysis in the 1920s and her subsequent rise to prominence in the field due perhaps to her close relationship with Sigmund Freud. The series documents her willingness to expend her personal influence and financial resources on behalf of individual psychoanalysts, psychoanalytic organizations, and publishing endeavors in France and elsewhere. Letters from René Allendy, A. Hesnard, Jacques Lacan, René Laforgue, Daniel Lagache, Sacha Nacht, Charles Odier, George Parcheminey, Edouard Pichon, Raymond de Saussure, and other French psychoanalysts illuminate her role in the establishment and development of psychoanalysis in France. Bonaparte's role in facilitating the emigration of psychoanalysts, most notably Sigmund Freud, from Nazi-controlled countries prior to World War II and the immigration of European analysts to the United States after the war is also documented. The geographical range of Bonaparte's correspondence reflects the extent of the psychoanalytic movement's diaspora and the breadth of her activities and associations.

The Subject File series contains correspondence from the International Psycho-Analytical Association and the Internationaler Psychoanalytischer Verlag, information concerning Bonaparte's purchase of Freud's letters to Wilhelm Fliess in 1937, obituaries and genealogical notes, and a photograph of Bonaparte. Other files relate to Margaret Williams, an American child analyst in Paris who was sued by the French medical establishment for practicing medicine without a medical degree. Included are letters from psychoanalysts pertaining to lay analysis in various countries, copies of interrogatories and depositions, newspaper clippings, and notes by Bonaparte providing an historical survey of lay analysis. Also included in the series is a proposal sent by Bonaparte to William C. Bullitt and Franklin D. Roosevelt in late 1938 recommending that the United States purchase Baja California from Mexico and establish a Jewish refugee state there. Bonaparte noted that she had developed the plan in consultation with Freud.

A small addition contains Bonaparte's notes on Sigmund Freud's letters to Wilhelm Fliess that came open for research use in 2010.

The bulk of the Bonaparte Papers was closed to research use until January 2020. The Formerly Closed series includes Bonaparte's journals dated 1913-1927 and 1959-1961; her dream journals dated 1923-1961; unpublished portions of her memoir; and a series of five original notebooks and watercolor drawings created by Bonaparte as a child that became the basis of her book, Cinq cahiers écrits par une petite fille entre sept ans et demi et dix ans et leurs commentaires. Also in the series are short writings by Bonaparte, many of which are autobiographical. The correspondence includes typescripts of letters exchanged between Bonaparte and the French statesman Aristide Briand between 1914 and 1931. The collection also contains a large number of letters exchanged by Freud and Bonaparte between 1925 and 1939. Also included are a series of notebooks in which Bonaparte recorded the progress of her analysis with Freud.