Abstract: We study the large observed changes in labor supply by married women in the United States over the post-World War II period, a period that saw little change in the labor supply by single women. We investigate the effects of changes in the gender wage gap, the quantitative impact of technological improvements in the production of nonmarket goods, and the potential inferiority of nonmarket goods in explaining the dramatic change in labor supply. We find that small decreases in the gender wage gap can simultaneously explain the significant increases in the average hours worked by married women and the relative constancy in the hours worked by single women and by single and married men. We also find that the impact of technological improvements in the household on married female hours and on the relative wage of females to males is too small for realistic values. Some specifications of the inferiority of home goods match the hours patterns, but they have counterfactual predictions for wages and expenditure patterns.