This article investigates how the introduction of gender quotas affected female representation in an open-list proportional representation system. Based on the Polish parliamentary elections of 2005, 2007, 2011, and 2015, it attempts to explain the gap between the share of female candidates and the share of female legislators. The authors estimate changes in individual electoral chances using logistic regression. Subsequently, counterfactual reasoning is applied to display the results in the metrics of seat shares. The analyses of candidate-level data demonstrate that after the introduction of quotas, significantly more women ran for office, but parties and voters, on average, changed their preferences to the disadvantage of female candidates, even when incumbency and previous electoral experience were controlled. The article demonstrates that women benefited from the introduction of quotas, but not right away. The desired effect of gender quotas (an increase in female legislative representation) was mitigated mainly by the unequal distribution of “electoral capital” among candidates of both genders. The impact of this factor was moderated by ballot ranking patterns. Once women acquire more electoral capital, the role of party elites’ negative bias in ballot ranking becomes more visible.