Until the 1970s, U.S. mortgage lenders commonly discounted half of the wife’s income in couples’ joint mortgage applications. This changed with the introduction of antidiscrimination legislation in the 1970s, providing a natural experiment to study the relaxation of income-related borrowing constraints. I study the effects of the reform by estimating difference-in-differences regressions and solving a simple calibrated life cycle model. I find substantial positive effects of the reform on mortgage borrowing and homeownership rates of married couples with working wives. Moreover, I find a positive effect on married womens labor force participation, which strongly amplifies the homeownership and borrowing effects.