Abstract Two images exist of the day-to-day practice of the EU comitology system. The first claims that comitology is deliberation by policy experts in which informal norms, deliberation and good arguments matter more than economic interests and formal voting rules. The second image portrays comitology as an arena for intergovernmental bargaining designed by the Member States to control the Commission. The article systematically investigates these images based on survey evidence from a questionnaire to the Danish and Dutch national representatives on nearly all comitology committees in 2006. The evidence suggests that both images hold and that their relative importance is determined by the nature of the issues dealt with by the individual comitology committees.