From 5 to 15 August 1984, a group of 79 physicists from 61 laboratories in 26 countries met in Erice for the 22nd Course of the International School of Subnuclear Physics. The countries represented were Austria, Belgium, Brazil, Bulgaria, Canada, People's Republic of China, Denmark, the Federal Republic of Germany, France, Greece, Hungary, Iran, Israel, Italy, Japan, Korea, Malaysia, Mexico, the Netherlands, Pakistan, Poland, Sweden, Switzerland, Turkey, the United Kingdom, the United States of America. The School was sponsored by the Italian Ministry of Public Education (MPI), the Italian Ministry of Scientific and Technologi cal Research (MRST), the Regional Sicilian Government (ERS), and the Weizmann Institute of Science. The programme of the School was devoted to a review of the most significant results in theoretical and experimental research work on the interactions between what we believe today are the point like constituents of the world: quarks and leptons. It should however not be forgotten that many problems are still to be understood: especially in the forefront of the correla tion between quarks and leptons. This game started in 1966 with the proposal for "leptonic quarks" and went on with "preons" and "rishons" just to quote the most famous attempts to unify these two worlds.

These proceedings cover the most recent advances in these topics keeping in mind their impact on observable phenomena. In addition they review the status and prospects of all known gauge forces, including the experimental results on their validity.

From August to September 1998, a group of 75 physicists from 52 laboratories in 15 countries met in Erice, Italy, for the 36th Course of the International School of Subnuclear Physics. This book constitutes the proceedings of that meeting. It reviews the present status of subnuclear physics and its connections with the fundamental problems of physics, such as the unification of all gauge forces.

The main focus of this year's Proceedings of the 53rd Course of the International School of Subnuclear Physics is the future of physics, including the new frontiers in other fields.

In August/September 2001, a group of 75 physicists from 51 laboratories in 15 countries met in Erice, Italy to participate in the 39th Course of the International School of Subnuclear Physics. This volume constitutes the proceedings of that meeting. It focuses on the theoretical and phenomenological developments in string theory, as well as in all the other sectors of subnuclear physics. In addition, experimental highlights are presented and discussed.

In August/September 1999, a group of 68 physicists from 48 laboratories in 17 countries met in Erice, Italy, to participate in the 37th Course of the International School of Subnuclear Physics. This volume constitutes the proceedings of that meeting. It focuses on the basic unity of fundamental physics at both the theoretical and the experimental level.

During July 1990. a group of 83 physicists from 43 laboratories in 21 countries met in Erice for the 28th Course of the International School of Subnuclear Physics. The countries represented were: Algeria. Canada. Chile. China. Czechoslovakia. Denmark. France. the Federal Republic of Germany. Greece. Holland. India. Italy. Pakistan. Peru. Poland. Sweden. Switzerland. Turkey. the Union of Soviet Socialist Republics. the United Kingdom. and the United States of America. The School was sponsored by the European Physical Society (EPS). the Italian Ministry of Education (MPI). the Italian Ministry of University and Scientific Research. the Sicilian Regional Government (ERS). and the Weizmann Institute of Science. The new topic discussed in some detail at the School was QCD phenomenology at 200 TeV. This energy frontier represents the goal for subnuclear physics after LHC and sse. The main lecturers were T.D. Lee. L. Cifarelli. Y. Dokshitzer and A. Ringwald. There are two possibilities. one optimistic. the other pessimistic. LHC and SSC can produce remarkable discoveries. In this case. the need to go to higher energies will be obvious. In the pessimistic case. LHC and SSC will produce the strongest evidence for the validity of the Standard Model. The need for higher energies will be impelled. In neither case can we wait. If the 200 TeV frontier is to be reached within our lifetime we need to start now: thinking and preparing the tools. Theory and R&D for future detectors are the basic points of the 200 TeV frontier.

The NATO Advanced Summer Institute 1978 was held at Karlsruhe from Sept. 4 to Sept. 16. The title of the school "New Phenomena in Lepton and Hadron Physics" relates to the present very exciting phase in particle physics. An impressive amount of experimental data has been collected in support of a fundamental new picture of the subnuclear world, - a picture which has found its theoretical formulation in Que~tum Chromodynamics and Gau~ theories. It is a general philosophy of the ASI to address the courses mainly to young and learning scientists, hence our major objective was to offer systematic reviews of both, the experimental situa tion and the basic theoretical concepts of the field. This volume contains the written versions of the major lectures delivered during the course. In addition several lectures and seminars had been scheduled in which also more original and specialized subjects were discus sed by invited speakers and participants of the school. Not all of these contributions are contained in this book.

This volume is a collection of lectures given during the 42nd Course of the International School of Subnuclear Physics. The contributions cover the most recent advances in theoretical physics and the latest results from current experimental facilities.In line with one of the aims of the school, which is to encourage and promote young physicists to achieve recognition at an international level, the students' recognized for their research excellence were given the opportunity to publish their work in this volume. Their contributions are joined by those from many distinguished lecturers in the field from around the world.

Particle physics seems to be entering a new period of consoli dation. In 1977 when the first summer institute on particles and fields was held at the Banff Center, the standard model of the electro-weak interaction was a promising model more or less con firmed; today it seems quite well-confirmed. QCD was considered as probably the correct theory of strong interactions; today most theo rists take it for granted. What seems to be lacking are computa tional tools and strenuous experimental testing; the major ideas seem to exist. Thus, this is a particularly auspicious time for a review of the status of theoretical and experimental particle physics and field theory. The lectures collected in this volume were presented from August 16 to August 27, 1981 at the Banff Center in Banff, Canada. The unifying theme was gauge fields and the topics covered dealt with electro-weak interactions, Q.C.D., sub-quarks and unified theories. The format of the Institute was as follows: thirteen lecture series of two to four hours each given by S. Brodsky, D. Bryman, M. Chen, S. Coleman, M. Creutz, H. Harari, J. Iliopoulos, C.H. Llewellyn Smith, P. Lepage, D. Perkins and L. Susskind. In addition there were nine seminars (one hour each) given by G. Bodwin, G. Bunce, M.