The gender wage gap is notable not just for its persistence and ubiquity but also for its variation across regions. A natural question is how greater work participation by women matters to female wages and the gender wage gap. Within India, a seeming paradox is that gender differentials in agricultural wage are the largest in southern regions of India that are otherwise favorable to women. Boserup (1970) hypothesized that this is due to greater labor force participation by women in these regions. This is not obvious as greater female labor supply could depress male wage as well. Other factors also need to be controlled for in the analyses. This paper undertakes a formal test of the Boserup proposition. We find that differences in female labor supply are able to explain 55 percent of the gender wage gap between northern and southern states of India.