This article asks, “What effect does the choice of a nation's electoral system have on the gender composition of its parliament over time?” I find that the electoral system has an important part to play, but previous work has overstated, by factors of between two and three, how much of a difference an electoral system can make. This article contributes an updated nonlinear theory of female representation, an improved dataset on women's representation across space and time, and more modern statistical techniques than previously used in research on this question.