[1] After his doctoral studies, Lehmann-Haupt spent time as a rare book dealer and assistant curator at the Gutenberg Museum in Mainz from 1927 to 1929.
[3] He immigrated to the United States in 1929 and started working for the Encyclopedia Britannica as an indexing editor.
[1] He also worked at the Morgan Library and was a visiting lecturer at the University of Illinois and Smith College.
[2] During World War II, Lehmann-Haupt served in London from 1944 to 1945, first as deputy chief of the U.S. German Policy Desk of the U.S. Office of War Information and then as psychological warfare officer at Supreme Headquarters, Allied Expeditionary Force (SHAEF).
[2] As part of his work in Berlin, Lehmann-Haupt was the first to analyze the records of the SS Ahnenerbe, revealing Heinrich Himmler’s archaeological activities in the USSR and Poland.
[2] From 1950 to 1968, he was a bibliographical consultant and, later, chief bibliography expert for rare books and a manuscript dealer H. P.