This article addresses the role played by members of interest groups in their groups’ activities and lobbying. One characteristic of interest groups today is stronger professionalisation. In order to actively and efficiently advocate the interests of their members in EU policymaking, interest groups are relying ever more on their staff. Interest group scholars argue that, as a consequence, members are becoming structurally distant from their groups as their role becomes less important. However, what remains unknown is how this increasing professionalisation affects the role of members in different types of organisations. To address this research gap, we analyse the role played by members in economic and non-economic interest groups. We argue that professionalisation has a negative impact on members’ role especially in non-economic interest groups, which is problematic because the professionalisation of these groups has been supported by EU institutions holding the ambition to make the EU more democratic but have in fact created an adverse effect.