subject matter and partly to help synthesise this expertise with the expertise in interstellar chemistry already present in the Group. The first fruits of this synthesis are contained in this volume. As it happened, this conference celebrated, not so much the beginnings of a long and fruitful collabo­ ration, but rather gave many of Alex's friends the chance to say a fond farewell as he departed UMIST at the end of January 1995 to take up a chair at UNAM, Mexico City. The core of this volume consists of twelve review articles, marked (R) in the list of contents, incorporating observational and theoretical studies of shock waves in a variety of situations from Herbig-Haro objects to Supernova Remnants to Active Galactic Nuclei. We have also included the contributed (C) and poster (P) papers.