Beatrice Lowenstein was born in 1879 in New York City to Benedict and Sophia (Mendelson) Lowenstein. Benedict (1831-1879) was born in the Rhineland in 1831 and immigrated to the United States in the middle of the nineteenth century. He settled in Memphis, Tennessee, where he and he brothers established a dry goods business, B. Lowenstein & Bros. The brothers made frequent trips to New York to buy goods for their business. While in New York Benedict met Sophia Mendelson (1848-1884). The couple married in 1867 and had six children: Adelaide, Leon Benedict, Florence, Sarah, Elsie, and Beatrice. Beatrice's father died shortly after her birth. Sophia died when Beatrice was only five years old. Benedict's brother, Bernard, became Beatrice's guardian. In 1907, Beatrice met Judah L. Magnes on a camping trip in the Adirondacks hosted by Louis Marshall (who married Beatrice's sister Florence). Magnes had just returned from a trip to a Zionist Congress in Palestine. During the same year, Beatrice attended the first meeting of the Hadassah Study Circle, a group of women, including Henrietta Szold, that met to discuss Jewish history and Zionism, topics in which Beatrice was becoming increasingly interested. Beatrice married Judah L. Magnes in 1908. At the time Judah was Rabbi at Temple Emanuel in New York and Chairman of the newly established Kehilla, the Jewish Community of New York City. The couple had three children: David, Jonathan, and Benedict. Between their marriage and the end of World War I, Beatrice and Judah lived in New York City and in Chappaqua, New York. In 1922, the Magnes family moved permanently to Palestine, where Judah L. Magnes was to become the first chancellor of Hebrew University in 1925. Beatrice Lowenstein Magnes died in 1968 in Israel.
The collection consists primarily of materials relating to Beatrice Lowenstein Magnes' extended family. Included are letters, notes and essays, poetry and plays, personal documents, Mendelson and Lowenstein family materials from mid-nineteenth-century Germany (including correspondence, a poem in honor of Sophia Mendelson on the occasion of her wedding, condolence letters, and bills), materials pertaining to Louis Marshall (Beatrice's brother-in-law) and James Marshall (Beatrice's nephew), drafts and manuscripts of Beatrice's memoir, Episodes (1977), and photographs. The photographs include images of members of the Lowenstein, Marshall, and Herzog families. Beatrice's sister, Elsie, married into the Herzog family. Her son, Paul Herzog, was chairman of the United States National Labor Relations Board under President Truman. Beatrice's sister, Florence, married Louis Marshall, the prominent attorney and leader of the New York Jewish community. There are photographs of both Paul Herzog and Louis Marshall in the collection.