- Pacific Northwest National Laboratory
- Partenaires INRAE
- Paul Scherrer Institute
- Payerne Aerological Station
- PennState Department of Chemistry
- PennState Meteorology Department
- Penn State System
- Pennsylvania Commonwealth System of Higher Education (PCSHE)
- Pennsylvania State University
- Physical Research Laboratory [Ahmedabad]
- Physics Institute [Bern]
- Physikalisches Institut [Bern]
- Physikalisches Institut [Bonn]
- Physikalisches Institut [Gießen]
- Physikalisch-Meteorologisches Observatorium Davos|World Radiation Center
- Physikalisch-Technische Bundesanstalt [Braunschweig]
- Physique Corpusculaire et Cosmologie
- Physique des plasmas
- Physique solaire
- Picomole Instruments Inc.
- Planetary and Space Sciences Research Institute [Milton Keynes]
- Planetary Science Laboratory [Ann Arbor]
- PLANETO - LATMOS
- Polar Environmental Centre
- Polar Geophysical Institute of Russian Academy of Sciences
- Pôle Astronomie du LESIA
- Pôle de recherche pour l'organisation et la diffusion de l'information géographique
- Pôle Planétologie du LESIA
- Polska Akademia Nauk = Polish Academy of Sciences = Académie polonaise des sciences
- Pomona College
- Pontificia Universidad Católica Argentina
- Princeton Institute for the Science and Technology of Materials
- Princeton University
- Purdue Climate Change Research Center
- Purdue University [West Lafayette]