This article aims to contribute to the growing literature on the substantive representation of women in conservative parties by evaluating MPs’ claims to ‘act for women’ during parliamentary debates on reproductive health and same-sex marriage in the UK and Australia. It argues that the actions of centre-right MPs who made claims about the situation of women in their speeches can be understood as the substantive representation of women, but the nature of this representation is problematised. While some legislators’ actions can be understood as a ‘feminist’ substantive representation of women, the action of MPs who supported liberalising reforms can be broadly understood as a different kind of ‘conservative’ substantive representation of women, which aims to address women’s status in a more traditional way. This can be differentiated from the actions of a group of conservative MPs who claimed to ‘act for women’ but did not seek to address women’s position (even in a traditional way), which is considered conversely as the representation of conservative interests. This article argues that to fully understand MPs’ legislative behaviour in Westminster democracies, consideration of an MP’s ideological view must be central to any explanation of the substantive representation of women on ‘morality politics’ issues.