There is a relationship between the different means of action of pressure groups - aimed at exerting pressure on the national government - and its effectiviness on policy level. Because a theoretical analysis is indispensable for further emperical research, the study first focuses on a general survey of possible means of action. This theoretical scheme is applied to four pressure groups. The analysis ofJour quite different pressure groups: 'Vrouwen Overleg Komitee', 'Bond Beter Leefmilieu', 'Vlaams Artsensyndicaat' and 'Belgische Boerenbond' shows that (...) the use of indirect means of action produces a greater effectiviness on policy level. But the choice of the means of action by an organisation depends on several determining factors. Following hypothesis can be sustained by this emperical study: stronger pressure groups, like Vlaams Artsensyndicaat and Belgische Boerenbond, mostly use indirect means of action and are characterised by a greater effectiviness than the two other organisations. (shrink)