This book is a state-of-the-art reference handbook of Participatory Design. Participatory Design is about the direct involvement of people in the co-design of the technologies they use. Its central concern is how collaborative design processes can be driven by the participation of the people affected by the technology designed. Participatory Design embraces a diverse collection of principles and practices aimed at making technologies, tools, environments, businesses, and social institutions more responsive to human needs. It brings together a multidisciplinary and international group of software developers, researchers, social scientists, managers, designers, practitioners, users, cultural workers, activists and citizens who both advocate and adopt distinctively participatory approaches in the development of information and communication artefacts, systems, services and technology. The book demonstrates why Participatory Design is such a valuable approach to thinking about design. It explains why Participatory Design is an important, highly relevant and most rewarding area for research and practice.