The recent election cycles of Latin American parliaments have seen increased women's representation in some states and a stalemate or even reduction in others. Argentina consistently has among the highest legislative representation for women in the world. Under what conditions do women achieve high rates of legislative representation? I will approach this question by assessing the leading theories, using comparative regional data, and analyzing the successful implementation of the Ley de Cupos in Argentina. I argue that the closed-list proportional representation system in which the Argentine enforced quota structure exists is the most effective condition for women to obtain a high percentage of legislative positions.