A common assumption in interest group literature is that lobbying success is a function of information supply and demand. This paper tests this expectation empirically with respect to the European Parliament (EP), based on a new dataset on interest groups’ preferences and information provision with regard to 29 legislative proposals (comprising 56 conflictive issues). The analysis indicates that, ceteris paribus, the rapporteur’s draft report and the report adopted by the responsible EP committee reflect the preferences of groups that provide more technical information to the EP. The provision of political information also has a positive effect on success at the draft report stage. However, I do not find support for the theoretical expectation that the effect of information supply varies at different levels of information demand. The findings provide new insights into the role and influence of interest groups in the EP and contribute to our understanding of EP decision-making.
