The XII International Colloquium on Croup Theoretical Methods in Physics took place at the Internationa] Centre for Theoretical Physics in Trieste, Italy, September 5-11, 1983.The purpose of the Colloquium has been to bring together scientists active in the several fields of theoretical physics in which group theoretical methods are used. The Colloquium included invited general talks aijncd at giving all participants an outline of the uses of group theoretical techniques in the various branches of physics, and specialized contributions presented as seminars or posters.