This article provides a comprehensive analysis of Eurosceptic contestation within the legislative arena of the European Parliament (EP) from 2009 to 2019. Under what conditions do Eurosceptics vote differently from their Europhile peers? The literatures on European integration, party competition and policy types lead us to expect variation in Eurosceptic contestation across policy areas. Drawing on roll-call votes in the EP, we introduce two new measures of such contestation: Eurosceptic dissent, that is, the extent to which Eurosceptics diverge from the Europhile plurality, and integration polarization, that is, the extent to which Eurosceptics and Europhiles oppose each other as cohesive camps. Our two indicators show that Eurosceptic contestation is particularly pronounced when the EP votes on cultural, distributive and constituent issues. When voting on redistributive policies, in contrast, dissent and polarization are curbed by national and ideological diversity.
