The aim of the book is to explore the basis for design of decision support systems in different kinds of complex, collective modern work environments. Frequently, decision making has been analyzed and modelled in terms of isolated "decisions" made by one person. In reality, decision making is a continuous, inter-personal process aiming at dynamic control of the state of affairs in a work domain and several decision makers typically will co-operate in this control. Furthermore, decision making in social groups usually has been studied either from the economic, management, or sociological point of view, mainly having theoretic or normative prespectives. What is urgently needed for analysis of the implications of modern information technology is a cognitive approach to models of distributed decision making in actual, complex work settings. It is the aim of this book to identify the state-of-the-art of modelling such distributed decision making, to identify the problems posed by modern high tech systems, and to formulate promising research avenues. This volume is part of a publication series emerging from an international interdisciplinary study group on "New Technologies and Work (NeTWork)". NeTWork is sponsored jointly by the Werner-Reimers-Foundation (Bad Homburg, Federal Republic of Germany) and the Maison des Sciences de l'Homme (Paris). The NeTWork study group has set itself the task of scrutinizing the most important problem domains posed by the introduction and spread of new technologies in work settings.