| Abbreviation | Definition |
|---|---|
| TISS | The Institute for Security Studies |
| TJC | The Joint Commission (formerly JCAHO) |
| TJF | The James Foundation, Baltimore, Maryland |
| TJF | Thomas Jefferson Foundation |
| TJG | The Jamesan Group |
| TJI | The Jackson Institute |
| TJP | The Jackson Project |
| TKA | Teach Kids Algebra project |
| TKC | The King Center |
| TKC | The Knowledgeable Consumer |
| TKF | Tariq Khamisa Foundation |
| TKF | Textil-Kunst-Forschung (Textile Art Research) |
| TKF | The Kohn Foundation |
| TKN | Teens Kickin Nicotine |
| TL | Tough Love |
| TLA | Texian Legacy Association |
| TLC | Tennessee Llama Community |
| TLC | Transportation for Livable Communities |
| TLF | The Library Foundation |
| TLG | Through the Looking Glass |