The involvement of civil society in EU governance is widely interpreted as a right step in the direction of participatory democracy. Civil society associations are expected to communicate the concerns of citizens to Brussels, to engage in public deliberation with EU decision makers and stakeholders alike and thus to contribute to the emergence of a transnational public sphere. The paper puts these high hopes under empirical scrutiny. As effective participation calls for professionalisation, public interest associations have adapted their organisational structures. Our data suggest that by doing so public interest associations face a dilemma: The more they succeed to have their voice heard, the less they function as democratic transmission belts.