Politics and gender scholarship is increasingly seeking to understand the relationship between the presence of women in politics and gendered policy outcomes – the substantive representation of women (SRW). Yet its focus remains squarely on the activities of ‘critical actors’ in parliaments and women's policy agencies and on ‘feminist’ rather than ‘mainstream’ policy areas. In contrast, this article investigates the impact of feminist actors in a range of institutional settings on recent processes of welfare reform in the UK. It finds that the gendered welfare reform introduced by New Labour was initiated and pushed through by a coalition of committed feminist actors across a range of institutions. Crucially, the reforms relied on the existence of ‘strategic actors’ and ‘gate openers’, defined as feminist actors in positions of significant institutional power. It makes a contribution to the actor-centred SRW scholarship, develops an institutionalist approach to this research and identifies the need for a political economy perspective to understanding how women can shape policy outcomes.