Dual screening—the complex bundle of practices that involve integrating, and switching across and between, live broadcast media and social media—is now routine for many citizens during important political media events. But do these practices shape political engagement, and if so, why? We devised a unique research design combining a large-scale Twitter dataset and a custom-built panel survey focusing on the broadcast party leaders' debates held during the 2014 European Parliament elections in the United Kingdom. We find that relatively active, “lean-forward” practices, such as commenting live on social media as the debate unfolded, and engaging with conversations via Twitter hashtags, have the strongest and most consistent positive associations with political engagement.