This book focuses on design in the domain of human-computer interaction. Including a broad sampling of case studies as well as narrower theoretical or empirical studies, it includes consideration of educational uses of design rationale, methods for teaching it in industry, and applications to a variety of software and user interface/application domains. The volume promises to be the largest collection of work on design rationale ever assembled, and thereby to energize the considerable, widespread interest in this topic. It will also act as a focus for the existing but scattered work in this domain.