| Abbreviation | Definition |
|---|---|
| NIA | National Institute on Aging |
| NIAC | National Iranian American Council |
| NIAH | National Institute of Animal Health |
| NIAI | National Insurance Advocacy Initiative |
| NIAW | National Institute of Animal Welfare |
| NICARE | Northern Ireland Centre for Health CARE Cooperation and Development |
| NICAS | Northern Ireland Community Addiction Service |
| NICEF | National Information Centre of Earthquake Engineering |
| NICEF | Nightingale International Culture & Education Foundation |
| NICEIC | National Inspection Council for Electrical Installation Contracting |
| NICWA | National Indian Child Welfare Association |
| NICWJ | National Interfaith Committee for Worker Justice |
| NIDRC | National Illegal Dumping Resource Center |
| NIF | National Immigration Forum |
| NIF | National Infantrymans' Foundation |
| NIF | New Israel Fund |
| NIFL | National Institute For Literacy |
| NIFTY | National Initiative for Finding Talented Youth |
| NIIT | National Institute of Information Technology |
| NIKIA | Native Indian Kids In America |