The 6th Advanced Course in Theoretical Physics was held at the University of Cape Town, January 8-19, 1990. The topic of the course was "Phase Structure of Strongly Interacting Matter." There were ten invited speakers from overseas, each having up to six hours in which to present his field of research to a relatively small audience of about 50 participants. This allowed for the presentation of a broad, coherent and pedagogical review of the present status of the field. In addition there were several one-hour presentations by local participants. The main emphasis of the course was on the study...