The growing number of interest groups active at the international level intrigues many political scientists. Most current explanations of global lobbying emphasize strategic incentives, such as venue-shopping, arguing that interest groups consciously choose to enter the international domain. Although strategic behaviour is undoubtedly present, available resources within the groups’ environment and institutional opportunities at the domestic and the international level systematically constrain and enable such choices. I draw on studies in US and EU interest group mobilization, and investigate the effects of such contextual factors for interest groups that enter the international domain. More specifically this paper offers an explanation for variation in the amount and type of interest groups that lobby at the UNFCCC over the past 15 years. Most prominently, I focus on the effects of domestic variables (i.e. economic, social and political factors), the political attention at the UNFCCC for certain issues, and competition effects on the number of interest groups stemming from different countries and regions in the world. The data-set thus allows me to identify which structural forces shape the strategic choices of interest groups that mobilize at the UNFCCC.
