The Increasing Effectiveness of National Gender Quotas, 1990–2010

National gender quotas—policies that require a certain percentage of women candidates or legislators—are becoming more effective over time. Using data on 145 countries from 1990 to 2010, we document this trend with latent growth‐curve models. Part of the explanation for increasing effectiveness is that countries have ratcheted up targets for women's inclusion and that quotas are increasingly written in ways that make them more effective at achieving stated goals. Activists, political elites, and policy makers have learned over time which quota policies are most effective, resulting in quotas with provisions that more often lead to success. But, changes in rules alone do not account for the increasing effectiveness of quotas over time. It appears that changing norms about women's incorporation in politics are also increasing quota effectiveness regardless of policy design.