Coal provides almost 40% of the world's electricity, and despite the understandable concern with respect to the environmental impact associated with coal use, forecasts from the International Energy Agency predict, that worldwide coal use will increase by up to 2% per annum until the year 2OlO. Faced with this increase, it is clearly important that the most efficient and environmentally acceptable clean coal technologies are available. This book is comprised of the proceedings of the Engineering Foundation Conference held in June 1993 in England. The objective of the conference was to present ideas on methods of predicting and reducing the effects of ash deposition in coal conversion systems, highlighting the problems experienced in industry, considering both utilities and industrial plants, and providing a view of the technology of coal ash deposition and its impact. Better techniques are needed to reduce the impact of ash deposition in coal fired plants, and these proceedings should form a reference document for anyone either experiencing slagging or actively engaged in trying to understand or eliminate the phenomenon.