By taking advantage of the Italian protest in 2009 in reaction to the behaviour of then Prime Minister Berlusconi, in this research, we investigated the role of sexist beliefs (i.e., hostile sexism, complementary gender differentiation, protective paternalism, and heterosexual intimacy) and group-based emotional reactions (i.e., anger, humiliation, and sadness) to women's and men's action mobilization against public forms of sexism. The findings of this study suggest that women and men engaged in this protest for different reasons. Women mobilized to express their anger at Berlusconi's sexist behaviour, an emotion related to the condemnation of hostile sexist views and benevolent sexist beliefs about heterosexual intimacy. In contrast, the strength of men's participation in the protest was affected by humiliation, an emotion related to the condemnation of hostile sexist beliefs and support for complementary gender differentiation. This emotional path suggests that men likely protested to restore their reputations. These findings underline the role of sexist beliefs and group-based emotions in transforming the condemnation of a sexist event into action mobilization against sexism for both women and men.