The Paul Scherrer Institute (PSI) is the largest research institute for natural and engineering sciences in Switzerland, conducting cutting-edge research in three main fields: matter and materials, energy and the environment and human health.

PSI develops, builds and operates complex large research facilities. Every year, more than 2500 scientists from Switzerland and around the world come to PSI to use our unique facilities to carry out experiments that are not possible anywhere else. PSI is committed to the training of future generations. Therefore about one quarter of our staff are apprentices, post-graduates or post-docs. For pupils it offers the school laboratory iLab.

PSI employs 2100 people, with an annual budget of approximately CHF 400 million, and is primarily financed by the Swiss Confederation. PSI is part of the ETH Domain, with the other members being the two Swiss Federal Institutes of Technology, ETH Zurich and EPFL Lausanne, as well as Eawag (Swiss Federal Institute of Aquatic Science and Technology), Empa (Swiss Federal Laboratories for Materials Science & Technology) and WSL (Swiss Federal Institute for Forest, Snow and Landscape Research). The Paul Scherrer Institute is located in the Canton of Aargau, in the municipal areas of Villigen and Würenlingen on both sides of the River Aare.