| On the Road | Kerouac, Jack | "Fiction - General"
| 310 | 1957 | 2 | 1993-01-23 |
| On the Run | MacDonald, John D. | "Fiction - Mystery"
| 224 | 1963 | 5 | 2015-07-22 |
| On the Water | Stone, Nathaniel | "Travel"
| 317 | 2002 | 7 | 2013-11-30 |
| On the Wing | Tennant, Alan | "Nature/Science"
| 301 | 2004 | 7 | 2005-03-12 |
| On War | Clausewitz, Carl von | "Philosophy"
| 310 | 1832 | 6 | 1995-11-05 |
| On Writing Well | Zinsser, William | "Literature/Essays"
| 294 | 1976 | 7 | 2002-02-27 |
| Once and Future King, The | White, T.H. | "Fiction - S. F./Fantasy"
| 639 | 1958 | 7 | 1998-04-20 |
| Once More Around the Park | Angell, Roger | "Sports"
| 351 | 1991 | 8 | 2022-12-18 |
| Once Upon a Telephone | Stern, Emily Gwathmey and Ellen | "Reference/Miscellaneous"
| 133 | 1994 | 5 | 2001-01-19 |
| One Corpse Too Many | Peters, Ellis | "Fiction - Mystery"
| 192 | 1979 | 8 | 1997-10-18 |
| One Day in the Life of Ivan Denisovich | Solzhenitsyn, Alexander | "Fiction - General"
| 158 | 1962 | 7 | 1994-11-20 |
| One Fearful Yellow Eye | MacDonald, John D. | "Fiction - Mystery"
| 224 | 1966 | 8 | 1989-07-13 |
| One Fish, Two Fish, Red Fish, Blue Fish | Seuss, Dr. | "Picture Book"
| 63 | 1960 | 7 | 1996-10-02 |
| One Flew Over the Cuckoo's Nest | Kesey, Ken | "Fiction - General"
| 272 | 1962 | 5 | 1997-08-02 |
| One for the Money | Evanovich, Janet | "Fiction - Mystery"
| 290 | 1994 | 8 | 2001-01-07 |
| One for the Road | Horwitz, Tony | "Travel"
| 206 | 1987 | 7 | 2014-05-11 |
| One Hundred Days | Schom, Alan | "World History - Military"
| 324 | | 6 | 1992-12-12 |
| One Hundred Years of Solitude | Marquez, Gabriel Garcia | "Fiction - S. F./Fantasy"
| 417 | 1967 | 4 | 2015-05-09 |
| One Man's Meat | White, E.B. | "Literature/Essays"
| 270 | 1942 | 8 | 2025-06-19 |
| One Man's Mountains | Patey, Tom | "Travel"
| 282 | 1971 | 4 | 2015-10-05 |
| One Man's West | Lavender, David | "Autobiographies, Memoirs and Biographies"
| 322 | 1956 | 6 | 2026-02-06 |
| One Monday We Killed Them All | MacDonald, John D. | "Fiction - Mystery"
| 192 | 1961 | 5 | 2015-08-09 |
| One More Spring | Nathan, Robert | "Fiction - General"
| 127 | 1933 | 6 | 2024-04-28 |
| One More Sunday | MacDonald, John D. | "Fiction - Mystery"
| 311 | 1984 | 5 | 2008-10-07 |
| One More Warbler | Emanuel, Victor | "Nature/Science"
| 252 | 2017 | 4 | 2019-01-31 |
| One Morning in Maine | McCloskey, Robert | "Fiction - Chapter Books"
| 59 | 1952 | 8 | 1998-12-08 |
| One of Our Thursdays Is Missing | Fforde, Jasper | "Fiction - S. F./Fantasy"
| 0 | 2011 | | |
| One Pitch Away | Sowell, Mike | "Sports"
| 320 | 1995 | 4 | 2025-06-06 |
| One Police Plaza | Caunitz, William J. | "Fiction - General"
| 371 | | 4 | 1989-09-12 |
| One Shot at Forever | Ballard, Chris | "Sports"
| 230 | 2012 | 6 | 2019-08-13 |
| One Summer | Bryson, Bill | "U.S. History - Cultural"
| 456 | 2013 | 7 | 2014-04-25 |
| Onions in the Stew | MacDonald, Betty | "Autobiographies, Memoirs and Biographies"
| 256 | 1955 | 6 | 2021-07-28 |
| Only Girl in the Game, The | MacDonald, John D. | "Fiction - Mystery"
| 224 | 1960 | 6 | 1990-04-15 |
| Only What's Necessary | Kidd, Chip | "Arts and Entertainment"
| 314 | 2015 | 6 | 2026-06-27 |
| Only Yesterday | Allen, Frederick Lewis | "U.S. History - Cultural"
| 237 | 1931 | 8 | 1987-11-15 |
| Open Boat and Other Stories, The | Crane, Stephen | "Fiction - Short Story Collection"
| 0 | 1897 | 8 | |
| Open Horizons | Olson, Sigurd F. | "Nature/Science"
| 227 | 1969 | 8 | |
| Opening the Gospel of John | Hawley, Philip W. Comfort and Wendell C. | "Theology"
| 341 | 1994 | 6 | 2010-04-09 |
| Oranges | McPhee, John | "Nature/Science"
| 149 | 1966 | 7 | 2003-11-25 |
| Orchid Thief, The | Orleans, Susan | "Nature/Science"
| 282 | 1998 | 6 | 2004-09-20 |
| Oregon Trail, The | Parkman, Francis | "Travel"
| 286 | 1849 | 8 | 1995-11-12 |
| Oregon Trail, The | Buck, Rinker | "Travel"
| 416 | 2015 | 6 | 2016-02-14 |
| Original Water-Color Paintings for The Birds of America, The | Audubon, John James | "Nature/Science"
| 431 | 1838 | 8 | 0000-00-00 |
| Oroonoko | Behn, Aphra | "Fiction - General"
| 78 | 1688 | 7 | 1998-01-30 |
| Orphans Preferred | Corbett, Christopher | "U.S. History - Cultural"
| 255 | 2003 | 6 | 2004-08-31 |
| Orthodoxy | Chesterton, G.K. | "Theology"
| 299 | 1908 | 8 | 2003-03-01 |
| Osterman Weekend, The | Ludlum, Robert | "Fiction - Adventure"
| 336 | 1972 | 7 | |
| Othello | Shakespeare, William | "Drama"
| 91 | 1604 | 6 | 1996-03-26 |
| Other 637 Best Things Anybody Ever Said, The | Byrne, Robert | "Humor"
| 160 | | 7 | 1988-12-09 |
| Other Times, Other Worlds | MacDonald, John D. | "Fiction - S. F./Fantasy"
| 282 | 1978 | 6 | 1999-08-10 |
