Consists, for the most part, of letters to American poet William Meredith (Princeton Class of 1940) from American authors, most of whom have been associated with Princeton.

Livingston T. Merchant was a diplomat and high-ranking government official. This collection consists of Merchant's papers, including correspondence, articles, notes, speeches, statements, interviews, clippings, printed matter, and personal papers.

Arthur Mendel was a prominent music scholar in the twentieth century and a professor at Princeton University. The collection contains correspondence with professional colleagues, course notes, musical notes, scrapbooks, and clippings. There is also additional unprocessed material from Mendel's time at Princeton.

Consists of 110 letters by influential magazine editor and critic H. L. Mencken to David Warren Ryder, a San Francisco area journalist, written mainly from Baltimore and New York between the years 1922 and 1947.

Horace and Thomas Meeker were father and son graduates of Princeton University. The papers document the University's admission processes circa 1925 and 1950.

Harold Raymond Medina (1888-1990) was a noted jurist, Princeton alumnus, and creator of a New York State Bar preparation course. This collection includes legal records, personal and professional correspondence, photographs, audio recordings, and teaching materials; in aggregate, they offer a substantial record of Medina's life and work.

Harold R. Medina was a well-known judge and active Princeton alumnus. These records document Judge Harold Medina's role as a trustee of Princeton University, a member of the Graduate Council, and a member of the advisory council for modern languages and literatures.

Consists of papers of Kenneth McKenzie (1870-1949), a former professor of Romance languages at Princeton, relating to fables.

George Stanley McGovern was a Congressman (1957-1961), a U.S. Senator (1963-1981), and a Democratic presidential nominee known for his strong liberal stance, particularly during the Vietnam War. This collection contains legislation files, campaign materials, correspondence, speech texts, schedules and invitations, travel files, patronage files, subject files, photographs, and audiovisual materials documenting McGovern's activities in the House of Representatives and in the U.S. Senate, as well as his time as Director of Food for Peace.

The collection consists of the editorial files and personal papers of Margaret K. McElderry. Publisher files include editorial correspondence, legal documents, and production files related to specific authors and publications.

Consists of manuscripts, correspondence, drawings, and other material of the author, journalist, and Princeton graduate (Class of 1905) Samuel Duff McCoy (1882-1964).

Consists of the selected writings and correspondence of American educator and writer, Grace Latimer Jones McClure. Materials primarily relate to her unpublished book, A Clippership Honeymoon, which centers around the diaries of Malvina "Mallie" McClure, the wife of a mid-19th century New England sea captain.

Consists of writings, diaries, correspondence, organizational records, clippings, and other personal papers of Irish poet Thomas McCarthy, including drafts of poetry, fiction, and nonfiction works from the 1970s through the 2010s; extensive diaries and notebooks on personal and literary topics; files related to his work with Cork 2005, the Triskel Arts Centre, and other cultural and arts organizations in Ireland; transcriptions and recordings of interviews and events; and teaching materials.

The McCarter Theatre was conceived as a permanent home for the Princeton University Triangle Club. McCarter began as a booking theater but ultimately moved into producing its own performances. The McCarter Theatre records document the history of the McCarter Theatre, including administration, performances and productions, and the building itself.

George McAneny served in numerous positions in the government of New York City, including president of the Borough of Manhattan (1910-1913), president of the Board of Aldermen (1914-1916), and chairman of the State Transit Commission (1921). This collection consists of lectures, reports, correspondence, committee and association files, clippings, scrapbooks, and photographs, all of which reflect his special interests in regional and city planning, zoning, city and state transit, and city financing.

Consists of writings, notebooks, correspondence, files from Time magazine, subject files, legal and financial correspondence, photographs, and printed material of T. S. Matthews, an author and editor of Time magazine.

H. Freeman Matthews, Jr., son of H. Freeman Matthews, was a career Foreign Service officer, serving with the State Department from 1952 to 1991. The collection consists of materials documenting Matthews, Jr.'s service with the State Department, in particular, his time as Deputy Chief of Mission in Cairo from 1976 to 1980.

Harrison Freeman Matthews Sr. (1899-1986) was a U.S. diplomat and career ambassador. This collection consists of correspondence, a draft of his memoirs, photographs, clippings, films and miscellaneous papers. It includes correspondence with Elizabeth Luke Matthews and a diary she kept during a visit to her husband in Vichy, France in 1940-42.

Dean Mathey (d. 1972), Class of 1912, was a member of the Board of Trustees and an ardent supporter of the University. The collection documents Mathey's familial relationships, service to Princeton, tennis career and other activities from his undergraduate days to the end of his life.

Consists of letters and other material related to Sylvia Beach (1887-1962), the American proprietress of the Paris bookshop Shakespeare and Company, collected by Jackson Mathews (1907?-1978).

Consists of selected material by and about the American poet Edgar Lee Masters, collected by Gertrude Claytor, a friend and fellow poet.

Alpheus T. Mason taught in the Dept. of Politics at Princeton University beginning in 1925 and authored a number of legal works as well as biographies of Supreme Court justices Harlan Fiske Stone and Louis D. Brandeis. This collection consists of papers of Mason, including material relating Stone, Brandeis and Woodrow Wilson.

José Martínez Sotomayor was a Mexican lawyer, judge, and writer who published novels, short stories, and nonfiction. His personal papers includes correspondence and autograph and typescript manuscripts of three of Martínez Sotomayor's books.

Consists of two distinct groups of papers of author Robert Bernard Martin: material relating to his scholarly research and writings on the English novelist and clergyman Charles Kingsley and manuscripts of eight of Martin's published novels and works of non-fiction.

Consists of scrapbooks of tearsheets and clippings, original artwork in pencil and in pen and ink, correspondence, financial documents, periodicals, permission agreements, and contracts spanning Henry Martin's career as a cartoonist and illustrator.

Anne Martindell was one of the first three women to serve in the New Jersey State Senate. After her four-year term ended in 1977, she served as director of the Office for Foreign Disaster Assistance, and was ambassador to New Zealand and Western Samoa for a two-year term. The papers document her career in politics and civil service, and also contain her unpublished memoirs and personal papers.

Consists of the papers of Allan Marquand, Princeton art professor, founder of the University's Department of Art and Archaeology, and first director of its Art Museum.

Julia Marlowe (1866-1950), who was also known as Sarah Frances Frost, was an American actress and Shakespearean performer. Her collection consists chiefly of letters to Ida Rissland Perscheid. Also included are photographs of both Marlowe and her husband, E. H. Sothern, articles by and about them, memorabilia, and scrapbooks of newspaper clippings.

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.