In the past 30 years, microfinance has carried many promises of social and economic transformation, with the shift towards targeting women being seen as a major strategic move through which the promise of social development could be most effectively delivered. However, ethnographic studies have shown that many women relinquish the use of their loans to male members of the household, belying the empowering promise of microfinance. We propose a simple model of household bargaining which examines how providing women with credit affects production and decision-making power in the household. Following Bergstrom (1996), we account for the roles of both divorce and non-cooperation in the household as relevant fall-back options in the bargaining strategy of each spouse. We show that the introduction of a microcredit programme is likely to have widely heterogeneous impacts, and can adversely affect the bargaining power of some women. We demonstrate that access to credit allows a woman to strengthen her bargaining position through an expansion of her autonomous activities (the causal mechanism hoped for) only under very specific circumstances: when she is able to invest her new capital profitably in an autonomous activity, and her husband has no alternative activity in which the same capital would generate comparable returns. The case in which the availability of credit is most likely to strengthen women's bargaining position in the household is when capital can be invested in a cooperative activity in which both spouses contribute in an important way.