The reviews in this volume address advances in three important but diverse areas of nuc1ear physics. Within nuc1ear physics it would be hard to provide a wider range of subject matter, style, or treatment. The first artic1e, on quark bags, is a pedagogic artic1e intended to make accessible to the nuc1ear physics community important new ideas from partic1e physics. The second, on interacting boson models, reviews a very interesting and controversial new approach to some of the central problems of nuc1ear spectroscopy. The third, on relativistic heavy-ion physics, is a guide to the extensive literature on a new subject which has been fuH of great expectations, puz zling data, and speculative ideas. In the past decade, partic1e theorists' understanding of the structure of hadrons has undergone a revolution strikingly similar to that brought about in nuc1ear physics by the introduction of the Iluc1ear sheH model. Like the sheH model, the bag model of hadrons phenomenologically specifies an interior region in which constituents are confined and described by single-partic1e wave functions that are only weakly perturbed by residual interactions.