Despite the growing importance of new technologies, research on individual opinion formation in the digital domain is still in its infancy. This article empirically examines citizens’ use of social media in the context of direct democracy. Based on previous work, we expect men to form their opinions on social media more frequently than women (gender gap hypothesis). In the second step, we focus on the contextual level by examining the role campaigns play in reducing this discrepancy. More specifically, we hypothesize that the presumed gender gap narrows in accordance with the increasing intensity of public debates that precede ballots (interaction hypothesis). The empirical analysis draws on 13 post-ballot surveys held at Switzerland’s federal level from 2016 to 2020 and supports both the gender gap and the interaction hypotheses.