This research considers three approaches to the study of populism: populism as an ideology, populism as a discourse, and populism as a strategy. We highlight the debates between these different approaches. Next, we take the most significant definition from each of the three approaches and rethink how populism as an ideology should be defined as fundamentally rooted in popular sovereignty. We then ground this discussion by applying each approach to a recent phenomenon in the European political arena, the Syriza party. Finally, we use discriminant analysis to identify the distinguishing characteristics of a Syriza party supporter. We find that this party’s supporters are less critical of the European Union, younger and more leftist than other recent neo-populist parties in Europe.