| Talbot, Marion. Papers |
| Taliaferro, Lucy Graves. Papers |
| Tannenbaum, Edward. Papers |
| Tax, Ervin Hanwit. Papers |
| Tax, Sol. Papers |
| Taylor, Bayard. Collection |
| Teichmann, Emil. Papers |
| Test Results for Railway Brake Shoes |
| Test, Francis W. Papers |
| The Printed Book: The Materials and Features of a Printed Book |
| Theatrical Portraits and Illustrations. Collection |
| Thelen, Herbert. Papers |
| Thoma, George F. Collection |
| Thomas, Roger, Reply to accusations made by Puritan ministers. Manuscript (Ms 109) |
| Thomas, William I., Papers |
| Thompson, Manley H. Papers |
| Thomson, S. Harrison, Collection of Photostats and Microfilms English Medieval Manuscripts |
| Thomson, Virgil. Papers |
| Thomson, William H. Clinical Notes of W. H. Thomson's Medical Clinic |
| Thorn, Edmund, A General History of Printing Wherein is Shewn the Origin of that Noble Art |
| Théorie de la fabrication des étoffes de soie |
| Tolman, Albert Harris. Notebooks |
| Towle, Charlotte. Papers |
| Townshend, George, Marquis Townshend, and Charlotte, Lady Townshend. Collection |
| Trattato delli orioli solari astronomici, ovvero la maniera di fare questi orologi orizzontali, verticali, e portatili ancora |
| Tribolet, Harold W. Archive on the Florence Flood |
| Triggs, Oscar Lovell. Papers |
| Tröltsch, Anton Friedrich, Freiherr von. Ohrenheilkunde |
| Tuckerman, Edward. A Synopsis of the Lichenes of New England, the Other Northern States, and British America |
| Tufts, James Hayden. Papers |
| Tuttleman Family, Edna S. and Stanley C. Collection of Nineteenth-Century Photographs |
| Tyler, Ralph W. Papers |