At the fertile interface between particle physics and astronomy, the field of particle astrophysics explores the cosmos using particle physics techniques and the subatomic world using astronomical observations. The particle astrophysics group at Penn State is helping to design, construct and analyze the data from vast detectors spread out on the South America pampas and on the flanks of the Sierra Negra volcano in Mexico, buried in the South Pole icecap and under the Black Hills of South Dakota, flown from enormous balloons in Texas and the Antarctic coast, and orbiting the earth on the International Space Station. These far-flung experiments will be used to study ultrahigh energy cosmic-rays, cosmological neutrinos, cosmic antimatter, dark matter, and many other astrophysical and particle physics phenomena. The Penn State group plays leading roles on the development of these instruments and on the analysis of the rich data harvest from them. Further information can be found at the web-page of the Institute for Gravitation and the Cosmos.Further information can be found at the web-page of the Institute for Gravitation and the Cosmos.