This book addresses the behavior of inorganic material in combustion systems. The past decade has seen unprecedented improvements in understanding the rates and mecha nisms of inorganic transformations and in developing analytical tools to predict them. These tools range from improved fuel analysis procedures to predictive computer codes. While this progress has been met with great enthusiasm within the research community, the practices of the industrial community remain largely unchanged. The papers in this book were selected from those presented at an Engineering Foundation Conference of the same title. All have been peer reviewed. The intent of the conference was to illustrate the application of advanced technology to ash-related problems in boilers and, by so doing, engage the research and industrial communities in more productive dialog. Those attending the conference generally felt that we were successful on these counts. We also engaged the industrial community to a greater extent than ever before in the conference discussion and presentation. We hope these proceedings will facilitate a continued and improved interaction between industrial and research communities. Behavior of inorganic material has long been recognized as one of the major considerations affecting the design and operation of boilers that burn ash-producing fuels. The practical problems associated with the behavior are sometimes catastrophic and spec tacular, ranging from major slag falls that damage the bottom of furnaces to complete plugging of convection passes.