Encyclopedias, Almanacs, Transcripts, and Maps
- 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
- Raphidioptera (Snakeflies)
- Rappaport, Roy A.
- Raprenox (Nitrogen Scrubbing)
- Rare Species
- rare-earth elements
- Rashīd Riḍā, Muḥammad
- Rastafarianism
- Rat-Kangaroos (Potoroidae)