Women are underrepresented in leadership positions in business, politics, and in the academic and scientific community. Not taking advantage of the skills of highly qualified women constitutes a waste of talent and, consequently, a loss of economic growth potential. To design effective policy interventions that empower women to reach leadership positions, it is crucial to identify at which levels of the career ladder they should be introduced. In a laboratory experiment, we run a two-stage tournament to evaluate the impact of three different interventions on women's willingness to compete for top positions. We find that, compared with no intervention, a gender quota introduced at the initial stage is ineffective in encouraging women to compete for the top, while quotas introduced in the final stage of competition or in both stages increase women's willingness to compete for the top, without distorting the performance of the winners.