This book is concerned with the machine-based generation of natural language text and presents a formal analysis of problems, which in the main have previously only been approached descriptively. In the process of producing discourse, speakers and writers must decide what it is that they want to say and how to present it effectively. Kathleen McKeown's main concern is to identify and formalise principles of discourse so that they can be used in a computational process. The text generation theory she describes has been embodied in a computer program, TEXT, which, given a question, can produce a paragraph length response. An Appendix to the book provides examples of the TEXT system in operation.