This publication has grown out of two frustrations. One is the experience that so many applications in the area of information and communication technology (lCT) are built without an eye to what the users can handle or need for their work, systematic user oriented evaluation of new tools is therefore limited. The video recorder provides a good general example of this phenomenon, but more worryingly so do many software tools designed for use in organisations. The other frustration arises from the fact that the people and the theories that can be used to provide this much needed user orientation are scattered over many disciplines and communities. There is considerable knowledge available about task performance, human communication and group interaction and the way in which new ICT -tools can be used to support these processes, but scientists do not know each other, the studies, theories, journals and conferences are produced by different communities in isolation and little cross fertilisation takes place. In this book I have tried to bring together knowledge from various disciplines, as the basis for constructing a design oriented evaluation approach that hopefully contributes to providing a user orientation for new (technical) systems.