Strengthening civil society as a domestic safeguard against the backsliding of reforms has become a cornerstone of the EU's enlargement policy. Support provided by the EU, however, was shown to have had limited effects in triggering civil society empowerment in candidate countries. This paper integrates insights from social movement and interest group research to study the diffusion of mobilization formats via transnational learning between activists from different enlargement rounds. It contends that such transnational exchanges between non-governmental organizations (NGOs) facilitated the empowerment of organised civil society in later countries. Drawing on comparative evidence from Serbia and Montenegro, it demonstrates how such transfers of external models enabled NGOs to feed into the ongoing membership talks. Their influence over substantive outcomes, however, was limited by a lack of domestic responsiveness, while funding availability constrained the operation of the transferred formats. These findings offer a fresh perspective on transnational contention in the context of Europeanisation and feed into the debate on civil society actors in enlargement countries.
