The 1984 Cargese Advanced Study Institute was devoted to the study of nuclear heavy ion collisions at medium and ultrarelativis tic energies. The origin of this meeting goes back to 1982 when the organizers met at the GANIL laboratory in Caen, France which had just started accelerating argon ions at 44 MeV per nucleon. We then realized that 1984 should be the appropriate time to review the first results obtained with such new kinds of facilities. The material contained in this volume, presenting many beautiful re sults on nuclei at high excitation, fully confirms this point. Many stimulating exchanges between experts in rather diffe rent fields already took place during the school and we hope that this cross fertilization will lead to further developments. About half of the present volume is also devoted to the field of relativistic heavy ion collisions, which is now expanding rapidly. As an illustration, let us recall that the construction of a 30 on 30 GeV per nucleon collider at Brookhaven has been recognized last year as one cf the major priorities by the US Nuclear Science Advisory Committee. We would like to express our gratitude to NATO for its ge nerous financial support which made this institute possible. We also wish to thank the Institut de Physique Nucleaire et de Physique des Particules (France), the Commissariat a l'energie atomique (France) and The National Science Foundation (USA) for the attribution of travel grants."

The present NATO Advanced Study Institute held in CARGESE (Corsica) from Au- gust 8th to August 18th, 1989 was devoted to Hadronic Physics. We tried to give this school a key educational role in this new and rapidly developing interdisciplinary field. We hope that the combination of the lectures and the open atmosphere of scientific exchange and inquiry afforded by the Cargese format has provided a unique educational and scien- tific opportunity for students and has brought together all the relevant concepts and issues for frontier research in this field. We would like to express our gratitude to NATO for its generous financial support which made this Institute possible. We also wish to thank Dr. Luis V. Da Cunha, Director of the Scientific Affairs Division, for his valuable comments and advice. We acknowledge the support of the Institut de Physique Nucleaire et de Physique des Particules (France), the Commissariat a l'Energie Atomique (France), and the U.S. National Science Fundation, for the attribution of travel grants. Our special appreciation is due to Frederique Dykstra for her oustanding organiza- tional work throughout the preparation and duration of this conference It is also a pleasure to thank the Universite de Nice for making available the facilities of the Cargese Scientific Institute. The pictures of the lecturers included in the present volume were kindly provided by one of the participants, Dr.R.Janner.