Correspondence, manuscripts, articles, book reviews, personal documents, clippings, scrapbooks and photographs relating to Lengyel's career and his research on the politics of Europe and Asia. Correspondents include Catherine Andrassy Karolyi, Mihaly Karolyi, H.L. Mencken, Ferenc Molnʹar and Leo Szilard. Of special note are Lengyel's extensive autobiographical writings, also outlines and manuscripts of his books including the unpublished "By Their Flame." There are clippings and photocopies of printed articles by Lengyel in English and Hungarian, published biographical information, book reviews and lecture programs. A series of scrapbooks contains clippings on the politics of Europe from 1920 to 1950.