The present volume has its source in the CAP-CRM summer school on "Particles and Fields" that was held in Banff in the summer of 1994. Over the years, the Division of Theoretical Physics of the Canadian Associa tion of Physicists (CAP) has regularly sponsored such schools on various theoretical and experimental topics. In 1994, the Centre de Recherches Mathematiques (CRM) lent its support to the event. This institute, located in Montreal, is one of Canada's national research centers in the mathe matical sciences. Its mandate includes the organization of scientific events across Canada and...