Topics include the new inflationary universe scenario; supersymmetry; Stephen Hawking's presentation, "The Cosmological Constant Is Probably Zero"; superunification and the seven-sphere; time as a dynamical variable; induced gravity; and an extensive and previously unpublished paper by Edward Witten on Kaluza-Klein theories. Contributors include Stephen L. Adler, Hans Bethe, M. J. Duff, Murray Gell-Mann, Alan H. Guth, Stephen W. Hawking, Roman Jackiw, Toichiro Kinoshita, W. E. Lamb, Jr., T. D. Lee, A. D. Linde, R. E. Marshak, Y. Nambu, K. Nishijima, John H. Schwarz, Silvan S. Schweber, Steven Weinberg, Victor Weisskopf, P. C. West, Edward Witten, and Bruno Zumino.