The Lilienthal family came from a valley in Schnaittach-Huttenbach, Germany, near Munich. The original family name was Seligmann. In 1814, Loew Seligmann registered his surname as Lilienthal (lily of the valley). The western branch of the family was descended from Rabbi Max and Dr. Sam Lilienthal (sons of Loew) and their wives, the sisters Pepi and Caroline Nettre. They all emigrated from Germany to the United States in the 1840s.
The collection contains a miscellany of Lilienthal family materials, including genealogical and biographical information; correspondence, including originals of Rabbi Max Lilienthal's letters from Russia sent to members of his family, fiancée and friends in the 1840s (in German), photocopies of letters (1880) from Theodore Max Lilienthal in New York to his brother Ernest Reuben Lilienthal in San Francisco discussing family matters and business problems, and photocopies of letters of congratulation on the occasion of the wedding of Sophie Gerstle and Theodore Max Lilienthal, and a photocopy of a letter from the artist Toby Rosenthal to Sophie Gerstle Lilienthal (1912) in which he describes the progress of her husband's portrait; a collection of Elizabeth Lilienthal's handwritten notes from the Sunday School of San Francisco's Congregation Emanu-El; a copy of a speech by Jesse Lilienthal; and photographs (including a photographic portrait of Pepi Lilienthal Samuels by Arnold Genthe).