On 19 March 1993, Raymond L. Orbach was inaugurated as the eighth Chancellor of the University of California, Riverside. In connection with this occasion, a two-day scientific symposium was held. Invited and contributed papers were presented on subjects related to 2 vital areas of condensed-matter physics in which Chancellor Orbach has made seminal contributions: the effects of disorder on magnetic behavior, and the theory of high-temperature superconductivity. The papers in this book, many of which are by outstanding contributors to these important fields, give an up-to-date overview of recent progress.