| Abbreviation | Definition |
|---|---|
| HHH | Homes that Help and Heal |
| HHHH | Head, Heart, Hands, and Health |
| HHI | Habitat for Humanity International |
| HHI | Hope Heart Institute |
| HHM | Helping Hands Monkeys |
| HHMC | Helping Hands Mission Camp |
| HHMI | Howard Hughes Medical Institute |
| HHN | Healing Heroes Network |
| HHSAD | Helping Hands Simian Aides for the Disabled |
| HHTFI | Hereditary Hemorrhagic Telangiectasia Foundation International |
| HHV | Help Hospitalized Veterans |
| HI | Harvest Institute |
| HI | Heartbeat International |
| HIA | Hobby Industries Association |
| HIA | Hobby Industry Association |
| HIAET | Housing Improvement Agency Education Trust |
| HIAS | Hebrew Immigrant Aid Society |
| HICS | Holt International Children's Services |
| HIFI | Hull International Fisheries Institute |
| HIKE | Hearing Impaired Kids Endowment |