This volume comprises the proceedings of a NATO Advanced Study Institute held in Geilo, Norway, between 8-19 April 1985. Although the principal support for the meeting was provided by the NATO Committee for Scientific Affairs, a number of additional sponsors also contributed, allowing the assembly of an unusually large number of internationally rec ognized speakers. Additional funds were received from: EXXON Research and Engineering Co. IBM (Europe) Institutt for energiteknikk (NorwaY) Institut Lauge-Langevin (France) The Norwegian Research Council for Science and Humanities NORDITA (Denmark) The Norwegian Foreign Office The U. S. Army Research, Development and Standardization Group (Europe) The U. S. National Science Foundation - The Norwegian Council for Science and Letters The organizing committee would like to take this opportunity to thank these contributors for their help in promoting a most exciting rewarding meeting. This Study Institute was the eighth of a series of meetings held in Geilo on subjects related to phase transitions. In contrast to previous meetings which were principally concerned with transitions in ordered systems, this school addressed the problems which arise when structural order is absent. The unifying feature among the subjects discussed at the school and the link to themes of earlier meetings was the concept of scaling.

This volume comprised the proceedings of a NATO Advanced Study Institute held in Geilo, Norway between 29 March and 9 April 1987. Al though the principal support for the meeting was provided by the NATO Cornrni ttee for Scientific Affairs, a number of additional sponsors also contributed. Additional funds were received from: Institutt for Energiteknikk (Norway) The Norwegian Research Council for Science and Humanities NORDITA (Denmark) VISTA (Norway) The organizing cornrni ttee would like to take this opportunity to thank all sponsors for their help in promoting an exciting and rewarding meeting. This Study Institute was the ninth of a series of meetings held in Geilo on subjects related to phase transitions and was a natural successor to the 1985 meeting on Scaling Phenomena in Disordered Systems. Many of the subjects discussed at the latter meeting were revisited in 1987, with time dependence as an added feature. Often the common theme was the concept of fractals first introduced into statistical physics some six years ago. However, by no means all disordered systems can be forced into a fractal framework, and many of the lectures reinforced this lesson.

This book comprises the Proceedings of a NATO Advanced Study Institute on Mu1ticritica1 Phenomena held in Geilo, Norway, between 10-21 April 1983. This school was the seventh to be held in Gei10, on various aspects of phase transitions. In spite of its apparently restrictive title the school was planned as a forum for the discus sion of phase transitions and instabilities in systems, with competing interactions and competing order parameters. Thus, in addition to the canonical multicritical points, subjects were diverse as critical phenomena in random magnetic systems and routes to chaos were discussed. The subject matter of the school is naturally divided into a series of categories which to some extent, reflect the historical development of interest in competing phenomena at phase transitions. Multicritical points in equilibrium systems, defined phenomenolo gically as points of sudden change of behaviour on an otherwise smooth phase boundary, were the first topics of the school. The theo retical consensus which has emerged during the past decade, largely as a result of calculations with the renormalisation group, was reviewed in some detail. The results presented, however, apply only to pure systems (in which dirt and other manifestations of reality are irrelevant) in that small realm close to the phase transition knoYln as "asymtopia."