Sister of John F. Kennedy. Red Cross volunteer (1940); research assistant to Frank Waldrop, Times-Herald Washington, DC (1941-1942); Program Assistant at Hans Crescent, Red Cross, London (1943-1944). Married William "Billy" Cavendish, the Marquess of Hartington, on May 6, 1944. Lady Hartington died on May 13, 1948 in a plane crash in France.
Material related to Kathleen Kennedy Hartington can be found in the Joseph P. Kennedy Papers (#136), the John F. Kennedy Personal Papers (#1), and the Rose Fitzgerald Kennedy Papers (#139). There are also photographs found in the Kennedy Family Photograph Collection.