This issue contains results presented at the Upstream Wave and Particle Workshop held at the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California on April 15--16, 1980. This overview article summarizes the results of the collective ISEE work. Several critical scientific problems remaining to be solved are mentioned with the hope that readers may be sufficiently aroused to attempt to study/solve them. In conclusion, some obvious astrophysical implications are discussed.