How transnational are European Parliament (EP) campaigns? Building on research on the European public sphere and the politicisation of the EU, this study investigates to what extent the 2019 EP campaign was transnational and which factors were associated with ‘going transnational’. It conceptualises Twitter linkages of EP candidates as constitutive elements of a transnational campaign arena distinguishing interactions with EP candidates from other countries (horizontal transnationalisation) and interactions with the supranational European party families and lead candidates (vertical transnationalisation). The analysis of tweets sent by EP candidates from all 28 member states reveals that most linkages remain national. Despite this evidence for the second-order logic, there are still relevant variations contingent on EU positions of parties, the adoption of the Spitzenkandidaten system and socialisation in the EP. The findings have implications for debates on the European public sphere and institutional reform proposals such as transnational party lists that might mitigate the EU’s democratic deficit.