We examine which Americans were likely to believe that American society has grown “too soft and feminine,” a concept we have characterized as gendered nationalism, and how such gendered nationalist attitudes influenced voting behavior in the 2016 presidential race. Our analysis shows that party, gender, education, and class shaped attitudes about gendered nationalism: Republicans, men, and members of the working class were more likely to support gendered nationalist views. We identify a strong, significant relationship between gendered nationalist attitudes and the probability of voting for Donald Trump, even after controlling for partisanship, ideology, race, religion, and other factors. Moreover, gender differences in candidate support were largely driven by gender differences in beliefs that the United States has grown too soft and feminine. Our research adds to the growing scholarly evidence indicating that gendered beliefs are likely to have a bigger impact on American political behavior than a voter's gender alone.