The rationale for government policies aimed at promoting market work by women is examined according to the criteria of efficiency and equity. Efficiency involves the issues of market failure and labor market discrimination. Equity involves the economic well-being of women compared to that of men. The case for interventionist policies on behalf of women is found to be weak on efficiency grounds but strong on equity grounds. It is suggested that conventional measures of labor market discrimination against women are hopelessly ambiguous, and an alternative measure of economic discrimination is proposed. Lifetime measures of income for men and women are constructed to measure this concept of discrimination, and it is shown that women are poorer than men throughout most of their adult lives.