Encyclopedias, Almanacs, Transcripts, and Maps
- Radioactive Fallout
- Radioactive Pollution
- Radioactive Waste Management
- Radiological Emergency Response Team
- Radionuclides
- Radiotracer
- Raëlians
- ragwort
- Rails, Coots, and Moorhens (Rallidae)
- Rails-to-Trails Conservancy
- Railway Passenger Service
- Rain Shadow
- Rainbow Snake
- Rainforest Action Network
- Rajiformes (Skates and Rays)
- Rajneesh
- Rajneesh, Shree
- Ramabai, Pandita
- Rangelands
- Rangi