Consists of material by and about Philip Wylie collected by Arthur and Sylvia Mandy during the course of their friendship with the American writer.

Osip Mandelʹshtam was a Russian poet, novelist, essayist and critic. A member of the Guild of Poets, a radical faction of the acmeist movement in poetry, he criticized the literary conformity demanded by Russia's new communist government. The collection consists of Russian-language works, correspondence, and printed matter of Mandelʹshtam. It contains holograph and typed manuscripts of his poems, reviews, articles, and essays, often in draft form representing different stages of his work, many of which are in the hand of his wife, Nadezhda, who acted as his amanuensis.

Consists of a complete duplicate archive of engineering drawings, calculations, letters, photographs, and various writings that document the numerous projects of Swiss civil engineer Robert Maillart.

Consists chiefly of letters by Alfred Thayer Mahan to his publisher regarding his writings about United States naval history. Mahan was a U.S. naval officer in the Civil War, and his work on the importance of adequate navies and merchant marines influenced the policies and philosophies of national leaders across the globe, including those of the 26th president of the United States, Theodore Roosevelt.

The John Van Antwerp MacMurray Papers describe the public and personal lives of John Van Antwerp MacMurray (1881-1960), diplomat and specialist in Far Eastern Affairs, and his father, Junius Wilson MacMurray (1843-1898).

Consists of selected manuscripts and correspondence of American poet/dramatist and Pulitzer Prize winner Archibald MacLeish.

The Helen MacInnes Papers contain the original manuscripts of twenty-two published novels, miscellaneous articles and speeches, and a play of renown Scottish novelist Helen MacInnes.

Consists of manuscripts and correspondence of Welsh writer Arthur Machen collected by Joseph Kelly Vodrey. It also contains an equal amount of manuscripts and correspondence of Machen admirers and collectors, particularly the members of the Machen Society, founded in 1948 after Machen's death.

E. Kimbark MacColl has written extensively on the history and politics of Portland, Oregon. Consists of notes, outlines, correspondence, and chapter drafts for MacColl's Ph.D. thesis, "The Supreme Court and Public Opinion: A Study of the Court Fight of 1937" (1953).

Harley L. Lutz (1882-1975) was an economist with expertise in taxation and public finance who spent his academic career at Oberlin College, Stanford University, and Princeton University. Lutz also served as an advisor on public finance, especially taxation, to the federal and state governments and was an outspoken opponent of increases in government spending. Lutz's papers document his career as an economist, as well as his work as a consultant on taxation and public finance, and include writings, reports, and correspondence.

Alfred J. Lotka (1880-1949), a statistician for the Metropolitan Life Insurance Company, was a significant contributor to the field of demography. He was a pioneer in the study of population dynamics and conducted research on the mathematical theory of evolution and the mathematical analysis of populations. Lotka's papers document his scholarship and his involvement in professional organizations and include drafts of his works, his notes and research materials, and correspondence.

Meir David Loewenstein was an Israeli politician who served on a number of early Israeli government bodies. The collection consists of official letters of the three Provisional Institutions active prior to the establishment of the State of Israel and during its first year of existence: The People's Council – Moetzet HaAm; The People's Administration – Minhelet HaAm; and The Provisional State Council – Moetzet HaMedina HaZmanit, later named The Constituent Assembly and eventually named: The First Knesset.

Howard A. Loeb served as chairman of the board of the Tradesmens Bank and Trust Company of Philadelphia, Pennsylvania and as representative of the Federal Reserve Bank of Philadelphia on the Federal Advisory Council. This collection consists of Loeb's correspondence and printed matter related to these positions.

Consists of correspondence files of Harold Loeb (Princeton Class of 1913), one of the founding editors of Broom, An International Magazine of the Arts.

The William W. Lockwood Papers document the American Institute of Pacific Relations and Lockwood's activities within the organization during the McCarthy era. A significant amount of the collection concerns the investigation of the Institute of Pacific Relations by Senators Joseph McCarthy and Pat McCarran. The collection also documents U.S.-Far East relations, particularly U.S.-Japanese trade and the Japanese textile industry.

Arthur S. Link was an author, editor, scholar and publisher, but is best known as the leading historian on Woodrow Wilson and for his leadership over the publication of Wilson's papers. This collection consists of the personal papers of Link, which includes articles, correspondence, notes, office files, and presidency records of the American Historical Association.

Charles A. Lindbergh and Anne Morrow Lindbergh were a famous twentieth-century aviation couple. The papers consist of manuscripts of Charles's A Letter to Americans and Anne's The Wave of the Future, A Confession of Faith, with related correspondence.

David Lilienthal served on the Wisconsin Public Service Commission (1923-1932), as a member of the board of directors (1933-1941) and then chairman (1941-1946) of the Tennessee Valley Authority (TVA), as first chairman (1946-1950) of the Atomic Energy Commission, and, later, in private business as an industrial consultant and chairman (1955) of the Development and Resources Corporation, which was involved with the Khuzestan Program in Iran. This collection consists of the papers of Lilienthal spanning his entire career, including correspondence, reports, articles, speeches, and printed matter.

Sir W. Arthur Lewis (1915-1991) was a pioneer in the field of economic development and a leading authority on economic growth in developing countries and associated political and social changes. He was a professor at the University of Manchester and Princeton University and served as an advisor to several governments. Lewis, who was from the Caribbean, also broke through racial barriers in the academic world throughout his career. Lewis's papers document his career as a scholar and as an economic advisor and include his professional correspondence, meeting minutes, reports, and writings.

David Kellogg Lewis (1941-2001) was an American philosopher who taught at Princeton University and the University of California, Los Angeles and contributed to metaphysics, philosophy of mind, philosophy of language, philosophy of mathematics, philosophy of science, decision theory, epistemology, meta-ethics, and aesthetics. Lewis's papers include over four decades of his correspondence with other philosophers and scholars, including David M. Armstrong, J. J. C. Smart, Frank Jackson, D. H. Mellor, M. J. Cresswell, Allen Hazen, John Bigelow, and others, as well as drafts of his articles, books, reviews, and unpublished writings with related correspondence, his undergraduate and graduate student papers and class notes, research materials from his time at the Hudson Institute, photographs of Lewis with friends and fellow philosophers, a group of files kept by the Australian philosopher David M. Armstrong regarding Lewis, papers of Stephanie R. Lewis, and family papers.

This collection contains the musical manuscripts, musical sketches, correspondence, teaching materials, business files, and other personal papers of American composer Frank Lewin (1925-2008), who resided in Princeton from 1951 until his death. Audio and video recordings on optical media and a hard drive include music, films, and interviews; digital materials also include photographs, documents, production information, scores, parts, copyright forms, and contracts.

The Esar Levine Collection of Frank Harris consists of the writings, correspondence, and printed matter of, and relating to, Frank Harris (1855-1931) as collected by Esar Levine (1899-?), Harris's disciple, agent and friend. Harris, an Irish-born, naturalized American citizen, was a prolific writer and journalist/editor who is perhaps best known for his scandalous autobiography, My Life and Loves, which was censored in America and parts of Europe.

John Lehmann was an English author, poet, journalist, editor, and publisher. His papers consist of letters from his literary friends, the correspondence of his family since the nineteenth century, manuscripts of his publications, financial and domestic files, and personal memorabilia.

Consists of the papers of Princeton art historian Rensselaer W. Lee, including correspondence, lectures, and manuscripts and notes for two published works.

The Ivy L. Lee Papers consist of personal papers and material from the public relations firm of Ivy Lee and Associates, documenting Ivy Lee's public relations theories and practice. Included are correspondence, diaries, articles, writings, public relations material, newsreels, and photographs reflecting Lee's interest in public relations, transportation (especially railroads), financial markets, and foreign relations, among others. Digital images of the Interborough Rapid Transit posters in Series 9 are available at Digital PUL.

Consists of nearly 300 letters from Simone de Beauvoir to Violette Leduc documenting their literary friendship spanning four decades, along with 23 notebooks containing manuscript drafts of Leduc's autobiography, La Bâtarde (1964).

William M. Leary (1934-2006) was an aviation historian who wrote his doctoral thesis on the politician H. Alexander Smith. The collection contains materials that Leary consulted in the process of writing his thesis, along with a manuscript of the thesis.

The Reginald Lawrence Papers consists primarily of typescripts of plays Lawrence (Princeton Class of 1921) wrote for theater, film, and television, as well as short stories, poetry, outlines and notes for various projects, some letters, photographs, and newspaper clippings.

David Lawrence, Princeton Class of 1910, was an American magazine and news service founder, editor, columnist, and author. This collection contains papers of Lawrence, including correspondence with notable twentieth century figures, articles, speeches, correspondent dispatches, radio broadcast transcripts, and manuscripts for several books.

Consists of manuscripts, correspondence, contracts, and clippings of the literary agency Laurence Pollinger Ltd. relating to the firm's involvement with the literary estate of D. H. Lawrence.

Consists of poetry manuscripts, drawings, and correspondence of the American poet R. Ellsworth Larsson (1901- ).

General Charles T. Lanham (1902-1978), a decorated WWII General and friend of author Ernest Hemingway, was an accomplished author, trainer, and after retiring from the military had a successful second career as a public relations executive. The Charles T. Lanham Papers document the general's WWII and post war military service and his private sector employment with several corporations. The papers contain correspondence, scrapbooks, photographs, journals, speeches, and legal documents.

Charles Trueman Lanham was a life soldier who retired as a general and was also friends with Hemingway. The papers consist of Xerox copies of correspondence between Lanham and Hemingway, a chronology of his time in World War II, correspondence about Hemingway, and a draft of Carlos Baker's biography of Hemingway.

Herbert Sidney Langfeld (1879-1958) was an American professor of psychology and prominent academic. This collection includes his diaries, professional correspondence, drafts of lectures and notes, photographs, and various printed material.

Consists of selected papers of Moses A. Lane, a nineteenth-century career serviceman in the U.S. Navy, serving most of his time as a gunner. Much of the material relates to a tour (1852-1855) in the Mediterranean aboard the sloop of war St. Louis.

This collection contains interview transcripts, cassette tapes, and background material collected by Peggy Lamson for her authorized biography, Roger Baldwin, Founder of the American Civil Liberties Union: A Portrait. Much of the background material was provided, and in some cases annotated, by Baldwin and documents both his professional and personal life.

Corliss Lamont was a humanist philosopher and socialist who served as a director of the American Civil Liberties Union (ACLU) from 1932 to 1954. The Corliss Lamont Papers document the breadth of Lamont's career as a humanist, civil libertarian, and philanthropist.