The focus on female MPs and leftist and feminist issues in traditional studies of women's substantive representation has supported the overall conclusion that women, feminists and left-wing parties promote women's interests in parliament. But our analysis of the ‘critical actors’ in women's substantive representation in 10 European countries confirms this finding only to a certain extent. Our inductive research design reveals an important group of less obvious actors: non-left, non-feminist and male MPs. That they speak out on behalf of women points to the necessity of revisiting our theories on women's substantive representation.