On the occasion of the fiftieth anniversary of the concept of anti-system party it is time to ask whether it enjoys good health in addition to longevity. Reflecting on what constitutes an anti-system party appears to be of unprecedented relevance, particularly in the light of the electoral success of populist parties such as the French Front National, the Five Star Movement in Italy and Syriza in Greece. This article highlights two crucial questions that remain unsolved if we follow existing conceptualizations: What are the boundaries of the concept? When does a party cease to be anti-system and how can it be reclassified thereafter? In order to overcome such limitations, this article develops a revisited concept of anti-system party and provides a set of guidelines for its empirical application. Furthermore, a novel typology capable of investigating the evolution of anti-system parties and classifying political parties in general is presented.
