Inter-organizational systems (IOS) are Information and Communication Technology (ICT)-based systems that enable organizations to share information and to electronically conduct business across organizational boundaries. Especially since the increasing availability of the Internet, there have been less technological barriers to implement IOS. However, that does not imply that IOS possibilities are implemented successfully in all occasions: other barriers may remain. Innovation is not only a technical process of 'solving problems'; it also involves economic and political processes in which interests are articulated, alliances are built and outcomes are struggled over. To explore this observation, this paper presents a model that helps to describe and analyze IOS from a power and interest perspective of multiple parties. To illustrate this model, eight case studies of IOS are discussed, of which one is in more depth. After that, we will put the findings of the analysis in a broader perspective. The paper concludes with the assertion that the scope for the design of an effective IOS depends on a combination of technical, economic and social factors, which are intertwined. The model may help users to assess and discuss these factors. (c) 2005 Elsevier Ltd. All rights reserved.