In the aftermath of the INTEREURO-project we launched several interest group surveys, including a large survey among EU level organized interests. The objective of these surveys was to develop systematic knowledge about the organizational development as well as the political strategies of civil society organizations, interest groups, lobby groups and advocacy organizations. What kind of challenges do these organizations face and how do they manage them? Our aim is to achieve a better understanding of the daily operations of civil society organizations across different national settings. For this purpose, we conducted a systematic mapping of the interest group populations in different European countries, including the EU-level. Large surveys were conducted at the EU-level, Lithuania, Poland, Slovenia, Belgium, Portugal, the Czech Republic, Sweden, and the Netherlands. More information, as well as data-sources, on this this Comparative Interest Group Survey Project can be found at a separate project website: www.cigsurvey.eu.