Primarily intended as an introduction to the ideas of formal specification, to form part of an undergraduate course in computer science and providing a new approach to the process of software development, based on the work of the Z community at the Programming Research Group at Oxford, the main emphasis of this book is on formal specification. Features include discussions of formal methods of program development from specifications, and management issues involved in the adoption of more formal approaches to software development. It introduces concepts from discrete mathematics which are relevant to formal specification and presents the basic ideas involved in rigorous methods of software development from formal specifications.