Democratic politics in Southern Europe has been shaken by the emergence of two new political parties: the Five Star Movement (M5S) in Italy and Podemos in Spain. Both were initially dismissed as ‘protest’ movements, tied to the particularly adverse effects of the European economic crisis on the southern part of the continent (Corbetta and Vignati 2013; Anderson 2014; Rodon and Hierro 2016; Gomez-Reino and Llamazares 2015). Over time, it has become clear that these phenomena are not as transitory as was initially assumed (Hartleb 2015; Bordignon and Ceccarini 2015). Commentators have begun to recognize that both the M5S and Podemos point to broader ‘structural transformations’ taking place within the region’s political systems (Diamanti 2014; Hobolt and Tilly 2016; Tronconi 2015; Ramiro and Gomez 2017; Sola and Ruendeles 2017). Interest in them has since burgeoned, but direct comparisons remain few and far between; almost none are in English (Rodriguez Aguileira De Prat 2015; Atte 2016; Giglioli 2016; cf. Borriello and Mazzolini 2017; Vittori 2017).