Lobbying is widespread in the European Union (EU). As of September 2012, no fewer than 5,270 interest representatives have signed up to the EU’s transparency register. In some instances, consultations organized by the European Commission attract several hundred responses. But how effective are these lobbying efforts? And which groups actually manage to influence EU decision-making? Existing research offers contradictory answers to these questions. Some studies find that concentrated, economic interests possess considerable influence; others conclude that societal interests are rarely able to sway decision-makers. A new dataset on the preferences of approximately thousand interest groups with respect to 80 legislative acts proposed by the European Commission between 2008 and 2010 allows us to evaluate these expectations. Our findings have implications for the literature on legislative decision-making in the EU and for the debate on the state of democracy in the EU.