The European Commission heavily depends on information from different interest groups when drafting policies. A major tool to get information about policy consequences are public consultations. However, interest groups can choose how much information to provide in their consultation submissions. Building on interviews with members of different directorate generals and interest groups, I developed a formal model to show that interest groups condition the amount of information they provide in consultations on the prior knowledge of the Commission. When the Commission has precise knowledge about possible consequences of policies, information barely affects the final policy proposal, and interest groups decide to invest less in information provision. Therefore, interest coalitions, interest groups with similar preferences, decide to send less informative signals to the Commission. When the commission has less precise beliefs, new information is an effective lobbying tool. Interest groups individually invest in providing new information, leading to more informative signals and more information aggregation in consultations. Using quantitative text analysis, I show that the similarity of submissions by different interest groups from the same lobbying coalition depends on the amount of information that the Commission has prior to the consultation. The less prior information the Commission has, the more information can be aggregated in consultations.