The European and American literatures on lobbying and interest groups developed largely separately in previous decades. Scholars developed different research foci with Europeans more commonly rooted in studies of policy systems and Americans more concerned with precise tactics of lobbying or on the membership calculus following from the work of Mancur Olson.Recent developments in the study of interest groups in Europe suggest that the literatures have begun to be much more closely aligned, a development that can be expected to accelerate in the future. We focus on three major points of convergence, giving illustrations and empirical evidence from the literature on each. First is the impact of governmental structures on the growth and development of national interest-group systems. Using examples from the US and the EU, we discuss the coevolution of groups and the state. Looking both over time and across issue-domains, groups are more active when and where the state is more active. Second, we look at the impact of government structures on the locus of advocacy. Originally explored in the U.S. context, multi-level governance structures in European settings have led to consideration of the concept of venue-shopping. Finally, we discuss the impact of government structures on advocacy behaviors, showing how groups in both systems adjust their lobbying strategies to their political context. Our review of findings and empirical developments in these three areas of interest-group research suggests that the study of groups, long divided by different perspectives may begin to benefit from substantially more convergence of research interests.2