Though more than 100 countries have adopted gender quotas, the effects of these reforms on women’s political leadership are largely unknown. We exploit a natural experiment—a 50–50 quota imposed by the national board of the Swedish Social Democratic Party on 290 municipal branches—to examine quotas’ influence on women’s selection to, and survival in, top political posts. We find that those municipalities where the quota had a larger impact became more likely to select (but not reappoint) female leaders. Extending this analysis, we show that the quota increased the number of women perceived as qualified for these positions. Our findings support the notion that quotas can have an acceleration effect on women’s representation in leadership positions, particularly when they augment the pool of female candidates for these posts. These results help dispel the myth that quotas trade short-term gains in women’s descriptive representation for long-term exclusion from political power.