| MacClintock, William D. Papers |
| MacDowell, Charles Henry. Papers |
| MacFarland, Faye Millard. Papers |
| MacNair, Harley F. Papers |
| MacRae, Donald Alexander. Papers |
| Maclean, Norman. Papers |
| Madison, James and Dolley Madison. Collection |
| Mailer, Norman. Manuscript of The Deer Park |
| Majima, Seigan. Majima Aammoku Ichibu No Gokui No Makimono |
| Malone, Virginia Eckels. Family. Papers |
| Maloof, John. Collection of Vivian Maier |
| Manby, George William. Sketches Made in Greenland |
| Mandel, Sidney W.. Collection of English Legal Documents |
| Manly, John Matthews. Papers |
| Manning, George, Adventures of a Half Guinea. Manuscript (Ms 626) |
| Manning, Richard. Band. Collection |
| Manufacturers of Toledo. Committee on Smoke Abatement. Majority Report of the Investigating Committee |
| Marcus, Ralph. Papers |
| Margolis, A. Fundamental Principles of Municipal Heating |
| Markwick, William. Danish Plants Found in the British Isles |
| Martin, August Eduard. Illustrations of Forcepses. Scrapbook |
| Martin, August Eduard. Notes |
| Martin, John. Book of Receipts |
| Martinez, Maria Elena. Papers |
| Maser, Edward. Papers |
| Materia Medica |
| Mathematics Manuscripts |
| Mather, Kirtley Fletcher. Papers |
| Mathesius, Johann, Joachimsthaler Chronica. Manuscript (Ms 68) |
| Mathews, Shailer. Papers |
| Matthews, Fred. Papers |
| Mauder, József. Letter |
| Max Mason. Papers |
| Maximow, Alexander A. Papers |
| Mayer, Albert A. Papers |
| Mayo-Smith, Richmond. Papers |
| McBurney, Charles. Papers |
| McCaul, Robert L., Jr. Papers |
| McDavid, Raven I. Papers |
| McDowell, Harold Louis. Collection of the Century of Progress Exposition |
| McKeon, Richard Peter. Papers |
| McLaughlin, Andrew Cunningham. Papers |
| McLean, Franklin C. Papers |
| McNeill, William H. Papers |
| McPartland, Jimmy and Marian. Collection |
| McQuown, Norman A. Papers |
| Mead, George Herbert. Papers |
| Mead, Irene Tufts, Collection of Alice Boughton. Photographs |
| Mead, Mildred. Photographs |
| Medical History, Correspondence |
| Medical Prescriptions |
| Medical Prescriptions and Other Recipes |
| Medical Tax Reports, Mecklenburg-Schwerin |
| Meisen, Vlademar. Treatment of Varices and Their Sequelae by Injection (Eczema and Ulcus Cruris) |
| Mencken, H. L. Collection |
| Mentschikoff, Soia. Papers |
| Merriam, Charles E. Papers |
| Merriam, Robert E. Papers |
| Metzler, Lloyd A. Papers |
| Meyer, Leonard B. Papers |
| Meyer, Peter. Papers. |
| Meynell, Alice. Collection |
| Michelson, Albert A. Papers |
| Michigan Governor's Committee to Investigate the Detroit Race Riot. Records |
| Middle Eastern Posters. Collection |
| Miles, Nelson Appleton. Collection |
| Mill, John Stuart. Collection |
| Milla, Karl, Die Flugbewegung der Vögel |
| Millard Avenue Woman's Club. Collection |
| Miller, Merton H. Papers |
| Mills, Ralph J., Jr. Papers |
| Milne-Edwards, Alphonse, Mammifères. Mélanges |
| Minerva. Records |
| Minnick, James L., University of Chicago Settlement Album |
| Mirsky, Marvin. Papers |
| Miyakawa Family Collection |
| Modern Cook, The |
| Modern Poetry Collection of Miscellaneous Manuscripts |
| Modern Poetry Little Magazine Collection |
| Modern Poetry Photograph Collection |
| Moedebeck, Herman, W.L. Papers on Aeronautics |
| Moffitt, George Wilbur. Papers |
| Monroe, Harriet. Papers |
| Montgomery, Mike. Collection |
| Moody, Harriet Brainard. Papers |
| Moody, William Vaughn. Papers |
| Moore, Carl R. Papers |
| Moore, Eliakim Hastings. Papers |
| Moore, James H. Papers |
| Morgan, Thomas J. Papers |
| Morgan, W. W. Papers |
| Morris, Edward House. Collection |
| Morris, Norval. Papers. |
| Morrison, Henry Clinton. Papers |
| Morton, Charles, Agency. Collection of American Popular Drama |
| Moscow Twelfth International Congress of Medicine. Scrapbook |
| Motion Picture Stills. Collection |
| Mulliken, Robert S. Papers |
| Mulliken, Robert S. Scientific Offprints Collection |
| Munting, Abraham. Phytographia Curiosa |
| Murdock, Fanny Bristol and Sarah Bristol Family. Papers |
| Murphy, William S. Papers |
| Musham, Harry A. The Graphic Solution of Triangles by Means of the Triangle Diagram/Graphic Calculation |
| Music Relating to the University of Chicago. Records |