This text directly addresses the question of how to bridge what has been termed the great divide between the approaches of systems developers and those of social scientists to computer supported co-operative work - a question that has been vigorously debated in the systems development literature. Traditionally, developers have been trained in formal methods and orientated to engineering and formal theoretical problems; many social scientists in the CSCW field come from humanistic traditions in which results are reported in a narrative mode. In spite of their differences in style, the two groups have been co-operating more in the last decade, as the people problems associated with computing become increasingly evident to everyone. The authors have been encouraged to examine in-depth, the theoretical basis of CSCW. With contributions from field leaders in the United Kingdom, France, Scandinavia and Mexico, as well as the United States, this volume offers an overview of the research and theory. It constitutes a foundation for the rapidly coalescing field of social informatics. Divided into three parts, this volume covers social theory, design theory, and the sociotechnical system with respect to CSCW. The first set of chapters looks at ways of rethinking basic social categories with the development of distributed collaborative computing technology - concepts of the group, technology, information, user and text. The next section concentrates more on the lessons that can be learned at the design stage given that one wants to build a CSCW system incorporating these insights - what kind of work does one need to do and how is understanding of design affected? The final part looks at the integration of social and technical in the operation of working sociotechnical systems. Collectively they argue that the social and technical are irremediably linked in practice and so the great divide not only should be a thing of the past, it should never have existed in the first place.