When multi-user computer systems are implemented in an organisational context they can have widespread impact on users and other stakeholders. There are many forms in which new technology can be implemented and each has different implications. The scenarios discussed in this paper are socio-technical system scenarios created early in the development process to help users and stakeholders understand the implications of different options and to assist them in formulating their requirements for future systems. The paper presents the results of using scenarios in nine field studies and six empirical studies. A process of developing and evaluating scenarios is described which relies on three different perspectives:(1) of the social and political characteristics of the systems development process (2) of socio-technical systems and the implications of new technical systems and (3) of the forms in which scenarios can be represented and participants can engage with them. The lessons and issues of developing and evaluating scenarios for these purposes are described, focusing upon the factors which affect the effectiveness with which participants can engage with the realization of the scenario.