This article takes gender inequalities in the distribution of power as its point of departure. Given the widespread evidence of the extent to which women, particularly poor women, have been marginalised in processes by which development policies are designed and implemented, it suggests that explicit attention needs to be given to strengthening women's capacity for voice and action at different stages of the planning cycle. In particular, there are certain ‘critical moments’ in the life of any intervention when the ideas, values and knowledge of key decision-making actors have a profound impact on how the intervention plays out in practice. The article sets out to develop a theory of change that addresses the issue of women's empowerment. It applies this theory to the critical moments framework. Finally, it draws on case studies of interventions funded by the Bill & Melinda Gates Foundation to illustrate key lessons for their transformative potential for women's empowerment.