The High Altitude Research Station Jungfraujoch, due to its unique location in an unspoiled high alpine environment at 3500m above sea level, the year-round accessibility via the Jungfrau Railway, and the excellent infrastructure, provides unique conditions for successful research in various disciplines. At present more than half of the projects concern environmental and climatic questions. The site, however, has also been playing a major role for pioneering work in the fields of high energy particle and cosmic ray physics.