Supernovae and their remnants play a vital role in the evolution of a galactic disk, both by injecting heavy elements and cosmic rays and by energizing the interstellar material. The medium surrounding the supernova determines the subsequent evolution of the remnant. The interaction between supernovae and their relics was the theme of IAU Colloquium 101, held in June 1987. This book is the official record of that meeting; it collects 12 invited review papers and 81 contributed papers. There are theoretical and observational contributions. With a surge of interest triggered by Supernova 1987A, this summary is particularly welcome.