The introduction of the European Citizens’ Initiative (ECI) has opened an institutional channel for cause entrepreneurs within the civil society to play “accountability politics” (Keck and Sikkink, 1998), using certain European Union (EU) values to legitimize political choices. The research question is how are European values mobilized in the context of the ECI? Five ECI initiatives are analysed, taking into account the public data available online and semi-structured interviews with the ECI promoters and supporters. The chapter shows how values are mobilized (and what specific values are used), what meaning is given to them and with what strategic purpose. It is argued that the mobilization of values in the context of the ECI is highly dependent upon the strategic vision of the role of civil society in the EU policymaking, distinguishing between initiatives that attempt to enter the policy cycle (realists) and those that challenge the Commission’s agenda or introduce new controversial topics (innovators). The conclusion is that the ECI has opened the possibility for the contestation of the meaning given to European values by civil society actors, therefore overcoming the taboo that they have represented so far.