Manifestos are an important channel for political parties to communicate their positions on a wide range of policy issues to both the electorate and the media to attract votes in an election. While a rich scholarly literature has evolved around the question of how party policy positions differ across time, countries and contexts, little is known about whether and how parties adapt the style of their manifestos in response to institutional changes in their environment. European Parliament (EP) elections provide an ideal case for studying this question since the EP has experienced major changes concerning its role and scope for policy-making since the first direct elections in 1979, therefore substantially changing the relationship with the electorate. I argue that given the EP’s empowerment alongside the need to secure an increasingly enlarged and polarized electorate’s support, parties competing in EP elections have normative and strategic incentives to draft simpler manifestos over time. I investigate to what extent parties are responsive to such institutional developments by analyzing changes in the complexity of their language in EP election manifestos from 1979 to 2019. The findings show that Euromanifestos overall have become more complex over time, which potentially is the result of increased policy complexity and a greater number of standpoints that need to be incorporated. However, there are substantial differences between parties and within manifestos depending on issue salience and issue ownership. The findings have implications for our understanding of parties’ responsiveness to institutional change.