When this book was first published in 1994, recent aspects of human factors research had led to methodologies that integrated usability into the development of interactive systems. MUSE was one of the pioneering methods for Usability Engineering. It provides an environment in which human factors contributions can realise their full potential. MUSE supports active human factors involvement in both design specification and evaluation, and takes system development from user requirements to user interface design. Its methods describe how design errors can be avoided or rectified throughout system development, as well as showing how errors can be identified and providing support for inter-disciplinary design planning and coordination. It therefore ranks as one of the best developed and most completely structured human factors methods. This book reviews the motivation for developing MUSE, and provides readers with a manual for method application. It will be essential reading for all involved with systems development, whether from the HCI or software engineering communities, and can be used as well for course accompaniment.