Collective action for other groups, such as men's action for women, has usually been analysed as social protest advancing equality of disadvantaged groups. In the current research, we extend collective action literature by applying SIMCA predictors-identity, injustice, efficacy-to investigate action in support of an advantaged group (women's action for men) and by distinguishing its progressive and reactionary forms. Across three online samples of women (Study 1: N = 1,825 US; Study 2: N = 679 UK; Study 3: N = 429 US), we show that support for reactionary action reinforcing male privilege is associated with outgroup identification and outgroup injustice. Conversely, progressive action supporting men in adopting egalitarian gender roles is associated with outgroup identification, outgroup-focused efficacy, and ingroup injustice.Importantly, some of these associations depend on the content of outgroup-focused variables. We discuss the implications of our findings for collective action and gender research.