Article révisé par les pairs
Résumé : Europarties are at the centre of the potential democratisation of European governance and their development is key to supranational representation. The authors will address the more general question of why Europarties have not so far shaped significantly European governance and policy by focusing on one of the main Europarties-the Party of European Socialists (PES). This article tests a number of claims about the factors accounting for weak Europarty influence over European Union (EU) governance. In this article, the authors discuss these claims by considering successively three complementary interrelated dimensions: the constraints placed upon the social democratic family by the EU institutional environment, the PES socio-economic policy offer and the collective action problem in relation to fighting European elections as a unified party on a unified platform. © 2014 Macmillan Publishers Ltd.