In every political system there is an inbuilt tension between how a government is supposed to be organized and operate and how it really functions. The official version of how a government is organized is always complemented and sometimes even contradicted by an informal version. How the informal structure or the shadow world of government is formatted, and by whom, is of crucial importance for how power and influence is distributed in a political system. This study has carried out an analysis of one part of the informal structure of the EU and its relationship with the formal structure. Thus the focus of the study has been on expert groups and their primary instigator-the Commission. In this framework three questions have been raised. Firstly, taking into account the Commission's tight to set up expert groups, to what extent is this tool used and what type of expert groups ere set up? Secondly, by what means does the Commission-in organizational terms-control the work of the expert groups? Thirdly, why ere expert groups set up and in what way can expert groups be used to model the decision-making structure of the EU
