Encyclopedias, Almanacs, Transcripts, and Maps
- nanometre
- Nanotechnologies
- Narrow-Mouthed Frogs (Microhylidae)
- Nāṣir-I Khusraw
- National Air Toxics Information Clearinghouse
- National Ambient Air Quality Standard
- National Emission Standards for Hazardous Air Pollutants
- National Estuary Program
- National Forest
- National Institute for the Environment
- National Institute for Urban Wildlife
- National Lakeshore
- National Mining and Minerals Act (1970)
- National Parks and Conservation Association
- National Pollutant Discharge Elimination System
- National Priorities List
- National Recycling Coalition
- National Research Council
- National Seashore
- National Wildlife Federation