I. Cosmic Rays and the Interstellar Medium.- A Brief Introduction to the Cosmic Radiation.- The Composition of the Cosmic Rays: An Update.- Interstellar Dust-Gas Relationships.- Dust, Gas and Cosmic Rays in the Interstellar Medium.- Comparison Between Greenberg and Mathis Models of Grains for the H2 Formation Induced by Cosmic Rays.- II. Supernovae, Acceleration, Propagation and Source Composition.- Shock Acceleration of Cosmic Rays.- Source Composition, Sites of Origin And Acceleration of Cosmic Rays.- Cosmic-Ray Age and the Interstellar Medium.- The Production of Antiprotons in the Interstellar Gas by Propagating Cosmic Rays.- The Source Composition of Galactic Cosmic Rays and the Condensation Process of the Elements in Circumstellar and Interstellar Gases.- The Distribution of Supernova Remnants in the Galaxy.- Gamma Rays from Supernova 1987A.- Acceleration of Cosmic Rays at Young Supernova Remnants.- The Effect of Relativistic Particle Beams on the Evolution of Supernova Envelopes: Self-Consistent Solutions.- Radio Spectral Variations in the Cygnus Loop.- III. Gamma Rays and Their Role as Cosmic Ray Tracers.- Gamma Ray Astrophysics at Energies up to 10 Gev.- Vhe and UHE Gamma Ray Sources.- Gamma-Rays from Electron, Proton Beam Interactions with Matter and/or Radiation: Application to Cygx-L, Geminga, and 3C273.- Gamma Rays and Neutrinos from Accretion Processes onto Collapsed Objects: Application to 3C273.- Nearby Galaxies in Highenergy Gamma Rays.- IV. Ultra-Energetic Cosmic Nuclei.- Cosmic Rays at the Highest Energies.- Participants.- Author Index.