Why is the gender gap in support for internationalism in Western Europe closing? Traditionally, women have been less supportive of processes of globalization – including free trade and European integration – than men. However, over the last two decades, this gender gap has been shrinking in several countries. In this paper, I argue that one of the reasons for this shrinking gender gap is the fact that opposition to globalization, European integration, and immigration are increasingly associated with right-wing extremism in these countries, as populist radical right parties and politicians have made anti-internationalism a key element of their platforms. Since women are on average less comfortable with extremism and more sensitive to the social stigma associated with the radical right, they increasingly move away from the policies these politicians and parties are known for. In turn, women are becoming more internationalist at a faster rate than men, producing the shrinking gender gap in support for internationalism. Using survey data drawn from the European Social Survey (ESS) and Eurobarometer surveys, as well as an unexpected event during survey design, I show that women’s attitudes toward internationalism are affected more strongly than men’s when anti-internationalism becomes associated with right-wing extremism. Results from an online survey experiment in France suggest that awareness of social norms surrounding extremism is a likely mechanism underlying this process. This research has important implications for our understanding of the role of gender in public opinion and how non-material factors shape attitudes toward internationalism.