Encyclopedias, Almanacs, Transcripts, and Maps
- Parrots and Parakeets
- Parsley Frogs (Pelodytidae)
- Parsons, Charles Algernon (1854–1931)
- Particulate
- Partnership for Pollution Prevention
- Parts per Billion
- Parts per Million
- Parts per Trillion
- Passenger Pigeon
- Passeriformes (continued)
- Passeriformes (Perching Birds)
- Passive Solar Design
- Passmore, John Arthur (1914 – ) Australian Philosopher and Writer
- Pasternak, Boris
- Patañjali the Grammarian
- Patellogastropoda (True Limpets)
- Patriarchy and Matriarchy
- Patrick
- Paucituberculata (Shrew Opossums)
- Pauck, Wilhelm