This paper extends the collective approach to household behaviour by proposing and estimating a model in which the weights attached to individual members are endogenously determined. The estimation is conducted using two different data-sets from three Indian states. We find that relative bargaining power of the adult decision-makers has a statistically significant effect on the budget share of an item and that the effects are typically nonlinear and vary significantly across items. This implies that household welfare is better protected in households where bargaining power is spread evenly between the spouses than where one partner enjoys a dominant position.