Cosmic rays are the only samples of matter that reach us from beyond the solar system. The particles provide us with clues as to the nature of their sources, the mechanism of acceleration, the interactions during their journey and the properties of the media they pass through. The relativistic ‘cosmic ray gas’ is itself a significant constituent of the interstellar medium. Cosmic ray research has interactions with other investigations in astrophysics, geophysics, and elementary particle physics. Some particles discovered in cosmic rays are even being applied to exploratory cancer therapy. Physicists who are planning the next generation of cosmic ray investigations (e.g., on isotopic composition, using the Space Shuttle) can benefit from contact with experts at the school. The explosive development of X- ray and gamma-ray astronomy and new knowledge in astrophysics, e.g., galaxy structure and dynamics, the nature of X-ray sources, pulsars and supernova remnants, advances in stellar evolution and nucleosynthesis, are all new and exciting approaches to cosmic-ray research. Indeed, the latter is helping to clarify these phenomena. Recent advances in cosmic ray propagation, such as the proof of the energy dependence of path length, observations of galactic radio-halos, exciting results on electrons, positrons and antiprotons, and new models of cosmic ray confinement, are influencing the design of future space experiments. The advent of DUMAND (Deep Underwater Muon and Neutrino Detector), a consortium dedicated to the search for high-energy cosmic neutrinos, is revealing new insights into astronomy and cosmology. Among the recent discoveries at lower energies, some aspects of interplanetary acceleration, the Jovian magnetosphere and the ‘anomalous component’ need to be clarified. At the upper end of the energy scale, particles of 1015 eV and their effects will be discussed.