The present volume contains the texts of the invited talks delivered at the Sev enth International Conference on Recent Progress in Many-Body Theories held at the University of Minnesota during the period August 26-31, 1991. The proceedings of the Fourth Conference (Oulu, Finland, 1987) and Fifth Conference (Arad, Israel, 1989) have been published by Plenum as the first two volumes of this series. Papers from the First Conference (Trieste, 1978) comprise Nuclear Physics volume A328, Nos. 1, 2. The Second Conference (Oaxtepec, Mexico, 1989) was published by Springer-Verlag as volume 142 of "Lecture Notes in Physics," entitled "Recent Progress in Many Body Theories." Volume 198 of the same series contains the papers from the Third Conference (Altenberg, Germany, 1983). These volumes are intended to cover a broad spectrum of current research topics in physics that benefit from the application of many-body theories for their elucidation. At the same time there is a focus on the development and refinement of many-body methods. One of the major aims of the conference series has been to foster the ex change of ideas among physicists working in such diverse areas as nucleon-nucleon in teractions, nuclear physics, astronomy, atomic and molecular physics, quantum chem istry, quantum fluids, and condensed matter physics. The present volume contains contributions from all of these areas.weiterlesen