Encyclopedias, Almanacs, Transcripts, and Maps
- Rites of Passage: North American Indian Rites
- Rites of Passage: Oceanic Rites
- Ritschl, Albrecht
- Ritual Studies
- River Basins
- River Dolphins
- Rnying ma pa (Nyingmapa) School
- road runner
- Rocky Flats Nuclear Plant
- Rocky Mountain Arsenal
- Rocky Mountain Institute
- Rodale Institute
- Rodentia (Rodents)
- Rohde, Erwin
- Rollers (Coraciidae)
- Rolston, Holmes (1932 – ) American Environmental and Religious Philosopher
- Roman Religion
- Roman Religion: The Early Period
- Roman Religion: The Imperial Period
- Ronsard, Pierre (1524 – 1585) French Naturalist and Poet