One of the central assumptions underlying the stakeholder model is that strengthened opportunities for involvement of non-state actors in political procedures hold significant promise for making those procedures more democratically legitimate. However, recent studies show that more open international organisations (IOs) are not perceived as more legitimate by non-state actors. In this article we explore one potential reason to explain this apparent paradox, investigating whether, and under what conditions, strengthened opportunities of stakeholder involvement enable the effective representation of global constituencies. The article shows that globalisation and politicisation of IOs go hand in hand with greater political activity by non-state actors defending domestic, rather than global, interests. Globalisation and politicisation may thus contribute to the exponential growth of the community of non-state actors active at IOs, but they do not make such community more globalised in nature. The article also illustrates that granting greater access to stakeholders in international institutions can somehow mitigate the effects of this underlying structural factors, and that institutional openness disproportionally fosters political activity by civic, rather than business, global stakeholders. We advance these arguments relying on a novel dataset including over eight thousand organisations active at the UN climate conferences and the WTO Ministerial Conferences.