Contains fulltext : 226843.pdf (Publisher’s version ) (Closed access) The European anti-austerity movement is generally associated with spawning leftist electoral projects, which exemplify the domestic institutionalization of activism. That the movement also generated a number of transnational coalitions with unusually broad and far-reaching ambitions remained somewhat under the radar. Projects like Alter Summit and DiEM25 seek to expand the anti-austerity movement’s struggle to the European level, by developing transnational organizational structures and challenging the political course of the EU. However, neither project managed to live up to its ambitions thus far and this article explores why. It argues that Alter Summit and DiEM25 represent attempts to create a transnational ‘modern prince’: a party-like organization that unites social movements around a counter-hegemonic strategy. While both managed to develop such strategies they also encountered challenges in facilitating democratic cohesion between transnational leaders and domestic supporters. This is partly the result of idiosyncratic shortcomings, but also reveals general challenges for transnational activism. 27 november 2020 16 p.