This research explores European ‘soft law’ and how it is used by interest groups. At the European level, soft law has been developing in many sectors and is one of the instruments that interest groups can use. Our reflection is based on the following question: How does European soft law impact on the strategies of interest groups at national level? Do they make specific use of it in the conduct of public action, how and under what conditions? In the first section, this article reviews the evolution of the institutional environment of interest groups and the multi-level European context in which they operate. We then address the issue of the use of legal instruments, more specifically soft law, by interest groups. Finally, we will set out the framework for the comparison and our survey protocol.