Common wisdom suggests that populist politicians use a simple language. While scholars have provided vast anecdotal evidence of populists’ plain speech style, the empirical literature on populist communication offers very few and mixed comprehensive evaluations of the complexity of elected officials’ language. This paper relies on a novel populist dictionary and 78,855 utterances from the 17th Italian parliament – March 2013–July 2016 – to comprehensively study the link between populism and speech complexity. We argue that ideological and electoral considerations lead populist parties and politicians to employ a straightforward language. Moreover, we claim that party membership shapes the rhetoric of elected officials, leading members of populist parties to use a simpler language. Using computer-assisted text analytic techniques to inspect parliamentary speeches given by the members of nine Italian parties, we perform a difference-in-differences analysis of the influence of party switching on legislators’ behaviour. Our results suggest that populist ideology, electoral strategy, and party membership influence legislators’ language complexity. Our overarching conclusion is that language simplicity might be thought of as a feature of populist communication. This arguably has implications for the ability of populist actors to use a simple communication style to outperform their mainstream counterparts when competing for voters’ support.