The policy engagement of interest groups in regulatory governance is a much debated and theorized phenomenon. A recurring theoretical assumption in those debates is that the playing field among stakeholders in the regulatory domain is even more severely tilted towards business presence than elsewhere. Such business dominance is then often associated with the phenomenon of regulatory capture, i.e. undue business influence on regulatory decision-making. Yet, studies of regulatory capture rarely test these assumptions by a systematic mapping of stakeholder mobilization. In this paper we empirically investigate patterns of mobilization in EU regulatory decision-making. We apply a unique regulatory-issued based sampling technique to map the stakeholders involved in the EU’s regulatory domain. This allows us to test issue-specific explanations for variation in stakeholder density and diversity, assess differences in policy engagement between business and citizen groups, and systematically compare the mobilization of interest groups across legislative and regulatory venues in the EU.
