Numerous studies have found that proportional electoral rules significantly increase women’s representation in national parliaments relative to majoritarian and mixed rules. These studies, however, suffer from serious methodological problems including the endogeneity of electoral laws, poor measures of cultural variables, and neglect of time trends. This article attempts to produce more accurate estimates of the effect of electoral rules on women’s representation by using within-country comparisons of electoral rule changes and bicameral systems as well as matching methods. The main finding is that the effect of electoral laws is not as strong as in previous studies and varies across cases. The policy implication is that changes in electoral laws may not provide a quick and consistent fix to the problem of low women’s representation.