- International Weekly Miscellany of Literature, Art, and Science — Volume 1, No. 4, July 22, 1850Author: VariousReleased on Project Gutenberg: July 29, 2004
- Into the Jaws of DeathAuthor: O'Brien, JackReleased on Project Gutenberg: August 2, 2006
- Introduction of the Locomotive Safety Truck: Contributions from the Museum of History and Technology: Paper 24Author: John H. WhiteReleased on Project Gutenberg: May 12, 2008
- Introduction to Infinitesimal Analysis; Functions of One Real VariableAuthor: Oswald Veblen, N. J. (Nels Johann) LennesReleased on Project Gutenberg: March 7, 2006
- Introduction to Non-ViolenceAuthor: Paullin, TheodoreReleased on Project Gutenberg: June 2, 2006
- Introduction to the Compleat AnglerAuthor: Andrew LangReleased on Project Gutenberg: December 1, 2000
- Introduction to the Dramas of BalzacAuthor: Epiphanius Wilson, J. Walker (Joseph Walker) McSpaddenReleased on Project Gutenberg: February 3, 2006
- Introduction to the Old TestamentAuthor: John Edgar McFadyenReleased on Project Gutenberg: December 1, 2004
- Introduction to the Philosophy and Writings of PlatoAuthor: Thomas TaylorReleased on Project Gutenberg: November 1, 2003
- Introductory American HistoryAuthor: Henry Eldridge Bourne, Elbert Jay BentonReleased on Project Gutenberg: February 1, 2006
- Invaders from the InfiniteAuthor: Campbell, John W., Jr. (John Wood)Released on Project Gutenberg: December 20, 2006
- Invisible LinksAuthor: Selma Lagerlöf, Pauline Bancroft FlachReleased on Project Gutenberg: December 6, 2004
- Iola Leroy; Or, Shadows UpliftedAuthor: Frances Ellen Watkins HarperReleased on Project Gutenberg: May 1, 2004
- IoleAuthor: Robert W. (Robert William) Chambers, Becker, Arthur C. [Illustrator]Released on Project Gutenberg: January 25, 2008
- IonAuthor: Plato, Benjamin JowettReleased on Project Gutenberg: February 1, 1999
- IonicaAuthor: William Johnson Cory, Arthur Christopher BensonReleased on Project Gutenberg: June 8, 2007
- Iphigenia in TaurisAuthor: Johann Wolfgang von Goethe, Anna SwanwickReleased on Project Gutenberg: May 18, 2005
- Iranian Influence on Moslem Literature, Part IAuthor: Konstantin Aleksandrovich Inostrantzev, G. K. (Gushtaspshah Kaikhushro) NarimanReleased on Project Gutenberg: July 16, 2004
- Ireland and the Home Rule MovementAuthor: McDonnell, Michael, Sir, John Edward RedmondReleased on Project Gutenberg: November 9, 2004
- Ireland In The New CenturyAuthor: Plunkett, Horace Curzon, SirReleased on Project Gutenberg: December 13, 2004
- Ireland Since ParnellAuthor: D. D. (Daniel Desmond) SheehanReleased on Project Gutenberg: November 5, 2004
- Ireland Under Coercion: The Diary of an American (1 of 2): (2nd ed.) (1888)Author: William Henry HurlbertReleased on Project Gutenberg: December 29, 2004
- Ireland Under Coercion: The Diary of an American (2 of 2): (2nd ed.) (1888)Author: William Henry HurlbertReleased on Project Gutenberg: December 29, 2004
- Ireland, Historic and PicturesqueAuthor: Charles JohnstonReleased on Project Gutenberg: April 1, 2004
- Irish Books and Irish PeopleAuthor: Stephen Lucius GwynnReleased on Project Gutenberg: August 8, 2007
- Irish Fairy TalesAuthor: James Stephens, Arthur RackhamReleased on Project Gutenberg: November 1, 2001
- Irish Ned: The Winnipeg NewsyAuthor: Samuel FeaReleased on Project Gutenberg: January 15, 2008
- Irish Plays and PlaywrightsAuthor: Cornelius WeygandtReleased on Project Gutenberg: August 11, 2006
- Irish Wit and Humor: Anecdote Biography of Swift, Curran, O'Leary and O'ConnellAuthor: AnonymousReleased on Project Gutenberg: September 8, 2006
- Irish Wonders: The Ghosts, Giants, Pooka, Demons, Leprechawns, Banshees, Fairies, Witches, Widows, Old Maids, and other Marvels of the Emerald IsleAuthor: D. R. (David Russell) McAnallyReleased on Project Gutenberg: October 7, 2006
- Iron Making in the Olden Times: as instanced in the Ancient Mines, Forges, and Furnaces of The Forest of DeanAuthor: H. G. (Henry George) NichollsReleased on Project Gutenberg: January 16, 2008
- Is Life Worth Living?Author: W. H. (William Hurrell) MallockReleased on Project Gutenberg: December 2, 2005
- Is Mars habitable? A critical examination of Professor Percival Lowell's book "Mars and its canals," with an alternative explanationAuthor: Alfred Russel WallaceReleased on Project Gutenberg: January 1, 2004
- Is Shakespeare Dead?: From My AutobiographyAuthor: Mark TwainReleased on Project Gutenberg: December 1, 2000
- Is Slavery Sanctioned by the Bible?Author: Allen, IsaacReleased on Project Gutenberg: February 13, 2008
- Is Ulster Right?Author: AnonymousReleased on Project Gutenberg: August 10, 2004
- Isaac Bickerstaff, Physician and AstrologerAuthor: Steele, Richard, Sir, Henry MorleyReleased on Project Gutenberg: May 1, 2001
- Isaac T. Hopper: A True LifeAuthor: Lydia Maria ChildReleased on Project Gutenberg: March 1, 2004
- Isabel LeicesterAuthor: Alma, Maude, -Released on Project Gutenberg: February 6, 2007
- Ishmael; Or, In the DepthsAuthor: Emma Dorothy Eliza Nevitte SouthworthReleased on Project Gutenberg: May 6, 2005
- Island Nights' EntertainmentsAuthor: Robert Louis StevensonReleased on Project Gutenberg: September 1, 1995
- Island Tales / On the Makaloa MatAuthor: Jack LondonReleased on Project Gutenberg: April 1, 2000
- Islands of SpaceAuthor: Campbell, John W., Jr. (John Wood)Released on Project Gutenberg: April 5, 2007
- Isle o' DreamsAuthor: Frederick Ferdinand Moore, Ralph P. (Ralph Pallen) ColemanReleased on Project Gutenberg: June 16, 2008
- IsmailiaAuthor: Baker, Samuel White, SirReleased on Project Gutenberg: January 1, 2003
- Isobel : A Romance of the Northern TrailAuthor: James Oliver CurwoodReleased on Project Gutenberg: October 1, 2004
- Isopel Berners: The History of certain doings in a Staffordshire Dingle, July, 1825Author: George Borrow, Thomas SeccombeReleased on Project Gutenberg: May 16, 2006
- Israel Potter: His Fifty Years of ExileAuthor: Herman MelvilleReleased on Project Gutenberg: March 20, 2005
- Issues in EthicsAuthor: Samuel Vaknin, Rangelovska, Lidija [Editor]Released on Project Gutenberg: June 1, 2005
- Issues in Population and BioethicsAuthor: Samuel Vaknin, Rangelovska, Lidija [Editor]Released on Project Gutenberg: July 1, 2005
- It can be doneAuthor: Joseph M. (Joseph Morris) Bachelor, St. Clair AdamsReleased on Project Gutenberg: January 1, 2004
- It Happened in EgyptAuthor: C. N. (Charles Norris) Williamson, A. M. (Alice Muriel) WilliamsonReleased on Project Gutenberg: January 1, 2006
- It Is Never Too Late to MendAuthor: Charles ReadeReleased on Project Gutenberg: November 1, 2003
- It Might Have Been: The Story of the Gunpowder PlotAuthor: Emily Sarah Holt, Irwin, M. (Madelaine) [Illustrator]Released on Project Gutenberg: June 19, 2008
- It's like this, catAuthor: Emily Neville, Weiss, Emil [Illustrator]Released on Project Gutenberg: March 27, 2008
- Italian HoursAuthor: Henry JamesReleased on Project Gutenberg: August 1, 2004
- Italian JourneysAuthor: William Dean HowellsReleased on Project Gutenberg: December 6, 2004
- Italian Letters, Vols. I and II; Or, The History of the Count de St. JulianAuthor: William GodwinReleased on Project Gutenberg: November 1, 2005
- Italian Popular TalesAuthor: Thomas Frederick CraneReleased on Project Gutenberg: November 26, 2007
- Italy at war and the Allies in the WestAuthor: E. Alexander (Edward Alexander) PowellReleased on Project Gutenberg: August 18, 2006