Why does lobbying success in the European Union (EU) vary across interest groups? Even though this question is central to the study of EU policy-making, only few have dealt with it. The small number of existing studies is moreover characterized by a multitude of hypotheses and contradictory findings. This article aims to overcome these shortcomings by presenting a theoretical exchange model that identifies information supply, citizen support and economic power of entire lobbying camps as the major determinants of lobbying success. The hypotheses are empirically evaluated based on a large new dataset. By combining a quantitative text analysis of interest group submissions to Commission consultations with an online survey among interest groups, the theoretical expectations are tested across a large number of policy issues and interest groups while controlling for individual interest group and issue characteristics. The empirical analysis confirms the theoretical expectations indicating that lobbying is a collective enterprise.